Stray Russian missiles were feared to have crossed into Poland on Tuesday, in what would be the first time Nato territory has been struck during the Ukraine war, as the Kremlin unleashed an intense attack on Ukraine that left 7m homes without power. Two people were killed in an explosion in an eastern Polish village, prompting the government in Warsaw to hold an emergency meeting – while the 100-missile attack on Ukraine was so serious that power supplies in a third country, Moldova, were also cut. The explosion in Poland destroyed a tractor in the village of Przewodów, about 3 miles (5km) from the border, on a day when the western Ukrainian city of Lviv was hit. Mateusz Morawiecki, Poland’s prime minister, urgently convened the country’s council of ministers for national security and defence, the government spokesperson, Piotr Müller, said – without immediately specifying the reason for the emergency meeting. After the meeting a Polish government spokesman said they were examining whether they needed to call an emergency Nato meeting, and were placing military units on heightened readiness. The White House also said it could not confirm reports coming out of Poland and was working with the Polish government to gather more information. The Russian defence ministry in a statement denied its missiles crossed into Poland, calling the reports a “deliberate provocation”. “The statements of the Polish media and officials about the alleged fall of ‘Russian’ missiles in the area of Przewodów is a deliberate provocation in order to escalate the situation. “No strikes on targets near the Ukrainian-Polish state border were made by Russian rockets. The wreckage published by the Polish media from the scene in the village of Przewodów has nothing to do with Russian weapons.” Some analysts said it was also possible a missile could also have come from a Ukrainian air defence system. Ukraine’s President Volodymyr Zelenskiy said the incident was a “significant escalation” of the conflict. Russian missiles hit Poland,” Zelenskiy said, according to a text accompanying his nightly video address. He did not provide evidence of the strikes. Some analysts said that they believed that photographs of missile debris at the scene were of a Ukrainian S-300 air defence system that would have been engaged in shooting down a Russian missile, but it was not possible to corroborate those reports. A deliberate attack on a Nato member could in theory lead to the invocation of the alliance’s article 5, which states that an attack on one member of the military alliance is considered an attack against all. But the Nato treaty is highly unlikely to be triggered by an accidental attack. Ukraine warned its energy situation was “critical” as a result of the Russian strikes, which hit 15 energy sites as well as residential buildings, with reports that half of Kyiv, 80% of Lviv and many other regions were without power. Water, heating and internet traffic were also disrupted – while the air raid sirens could no longer work because of the loss of electricity – in the most intense missile attack seen since the start of Russia’s autumn bombing campaign. Earlier Ukraine’s president, addressing the G20 by video link, called on the leaders to support Ukraine to end the war on its terms – the primary one being that Russian troops leave all of Ukraine, including the areas it occupied in 2014. President Volodymyr Zelenskiy, who had earlier addressed the world’s leaders in Bali with his peace proposals, released a short video message acknowledging the scale of the attack. “We are working, we will restore everything, we will survive,” he added. Russia began targeting Ukraine’s electricity grid last month, and waves of strikes have knocked outmore than 40% of the country’s energy infrastructure, as the country heads towards a winter where temperatures can reach -10C or even -20C. The attacks appeared deliberately timed for the middle of the two-day G20 summit – a wilful attempt by Russia’s Vladimir Putin to defy the majority of the international community, which was planning to release a communique condemning his country’s assault on his neighbour. The draft declaration included language noting “most members strongly condemned the war in Ukraine” and stressed that “it is causing immense human suffering and exacerbating existing fragilities in the global economy” – although the US continued to press for stronger criticism. Putin is not present at the G20 but his veteran foreign minister, Sergei Lavrov, complained of what he called the “politicisation” of the meeting, and blamed the west for unleashing “a hybrid war” in Ukraine before flying out of the meeting. Andriy Yermak, the chief of Zelenskiy’s staff, said missile strikes were a direct response to the president’s speech. “Does anyone seriously think that the Kremlin really wants peace? It wants obedience. But at the end of the day, terrorists always lose,” he added. Zelenskiy also called for the creation of a special war crimes tribunal and compensation for all the damage caused by the invasion. “We will not allow Russia to wait, build up its forces, and then start a new series of terror and global destabilisation. There will be no Minsk 3, which Russia will violate immediately after the agreement,” the president said, referring to the name given to two previous peace agreements from 2014 and 2015. Multiple waves of missiles were unleashed against Ukraine on Tuesday. Yuriy Ignat, a spokesperson for Ukraine’s air defence forces, said at 5.20pm Kyiv time that more than 80 rockets had been launched and 20 were still in transit. That exceeded the number launched on attacks on 10 October. Kyrylo Tymoshenko, the deputy head of Ukraine’s presidential administration, said the country’s energy situation was “critical” across the country. Strikes also hit Kharkiv and Poltava, Mykolaiv, Dnipro, Zhytomyr, Khmelnytskyi, Lviv, Volyn, Rivne, Cherkassy, Odesa, Kirovohrad and Chernihiv regions. “Most hits were recorded in the centre and north of the country. The situation in the capital is extremely difficult, special schedules of emergency shutdowns have been introduced,” Tymoshenko wrote on Telegram. He called on Ukrainians to use energy sparingly. Three residential buildings in Kyiv were among those hit, according to the city’s mayor, Vitaliy Klitschko. He said the buildings were in Kyiv’s Pechersk district, a residential area just north of the presidential administration. Klitschko said medics and rescue workers were on their way to the scenes – and that a body had been recovered from one of the buildings. Moldova’s infrastructure minister said the country had suffered a “massive power outage” for a time on Tuesday after one of its key power lines was automatically disconnected as a safety measure as a consequence of the bombing in Ukraine. “Russian aggression against Ukraine directly affects our country,” Andrei Spinu said. The mass strike follows Russia’s retreat from Kherson and the west bank of the Dnipro River last week, in which about 20,000 troops moved out in a relatively orderly withdrawal. Some in the west fear the fighting could become harder into the winter. One senior western official warned that fighting in Ukraine was likely to descend into a grind in which neither side is able to achieve a military breakthrough. The gloomy assessment – if proved accurate – would ultimately favour Russia because it occupies a large swathe of Ukrainian territory and comes amid warnings of ammunition shortages on both sides and the impending onset of winter. “If we take a big picture overall as we go into 2023, we are still expecting the grind. We are still expecting it to be largely static, and we still expect neither side to particularly win or lose, and really that extends all the way through 2023,” said the western official, who was speaking on condition of anonymity. The official also stressed that any predictions about the future course of the war remained difficult to make, not least because of the offensive creativity of the Ukrainian forces. “The Ukrainians continue to surprise us,” they added, a reference to autumn successes near Kharkiv and most recently in Kherson.