Vladimir Putin has blamed Ukraine directly for the blast at a vital bridge linking Russia and Crimea, describing the weekend attack as “act of terror” carried out by “Ukrainian secret services” amid growing expectation that the Kremlin plans an imminent and harsh escalation of its war. “There is no doubt. This is an act of terrorism aimed at destroying critically important civilian infrastructure,” the Russian president said in a video released on Sunday night on the Kremlin’s Telegram channel about the explosion on the Kerch bridge, which occurred on Saturday. “This was devised, carried out and ordered by the Ukrainian special services.” Putin spoke after meeting Alexander Bastrykin, the head of Russia’s investigative committee, who was presenting findings into the explosion and fire on the bridge. Bastrykin said he had opened a criminal case into an “act of terrorism” adding: “We have already established the route of the truck” which he said included transit through Bulgaria, Georgia, Armenia, North Ossetia, Krasnodar (a region in southern Russia) and other places. His remarks set the scene for an expected response by Moscow, with Putin convening his national security council on Monday to discuss the blast that hit the structure linking Russian-occupied Crimea to the Russian mainland. The blast on the bridge over the Kerch strait, a key supply route for Moscow’s forces in southern Ukraine, had prompted gleeful messages from Ukrainian officials on Saturday but no claim of responsibility. The bridge is also a major artery for the port of Sevastopol, where the Russian Black Sea fleet is based. The attack was a humiliating blow to Putin’s prestige, who personally opened the road section of the 12-mile bridge in 2018 and backed the $4bn construction. The bridge was viewed by Ukrainians as a hated symbol of Russia’s aggressively expansionist ambitions. Putin’s remarks came a day after the attack and the promotion hours later of hard-line general Sergei Surovkin as the first overall commander of Russian forces in Ukraine after increasingly public criticism of Moscow’s mounting military failures in recent weeks. Separately, Russia’s FSB security service claimed on Sunday it had seen a “considerable increase” of Ukrainian fire into its territory in recent days. “Since the start of October, the number of attacks from Ukrainian armed formations on Russia’s border territory has considerably increased,” said the FSB, which is responsible for border security. Taken together, the remarks amount to an ominous indication that Moscow may be planning to escalate the conflict with Ukraine – after a chorus of public demands from hardliners for retaliation. It also comes in the context of Russia’s growing nuclear brinkmanship around the nine-month-old war. Meanwhile in the latest violence at least 12 people were killed by Russian shelling of a residential area in Ukraine’s south-eastern city of Zaporizhzhia, a region the Kremlin illegally claims to have annexed despite not controlling all of it. In the immediate aftermath of the strikes, the city council said 17 were killed but later revised that down to 12. Regional police reported on Sunday afternoon that 13 had been killed and more than 60 wounded, at least 10 of whom were children. Images from the aftermath in Zaporizhzhia showed a nine-storey building in the city still burning and partially collapsed as rescue workers sought to retrieve the dead and wounded, with the regional governor, Oleksandr Starukh, warning there may be more people under the rubble. The city council secretary, Anatoliy Kurtev, said rockets had struck Zaporizhzhia overnight, and at least 20 private homes and 50 apartment buildings had been damaged. The Ukrainian president, Volodymyr Zelenskiy, described the latest attack as “absolute evil”. “Zaporizhzhia again. Merciless strikes on peaceful people again. On residential buildings, just in the middle of the night,” he said on Telegram. “Absolute meanness. Absolute evil. Savages and terrorists, from the one who gave this order to everyone who fulfilled this order. They will bear responsibility, for sure. Before the law and before people.” The strikes on Zaporizhzhia appear to be part of a deliberate tactic also used against other cities close to the conflict’s frontlines, including Kharkiv, Mykolaiv and Sloviansk, which have been struck repeatedly. Zaporizhzhia is close to the frontline where Kyiv’s forces have been carrying out a large-scale counterattack against Russian troops. The Ukrainian-controlled industrial city is in the Zaporizhzhia region, also home to the Russian-occupied nuclear plant that has been the site of heavy shelling. In recent weeks, Russia has repeatedly struck the city. At least another 19 people died on Thursday in Russian missile strikes on apartment buildings in Zaporizhzhia, which in turn followed a Russian strike on a convoy of civilian cars in the region that killed 30 just over a week ago. As Russia has tried to downplay the significance of the bridge attack, some nationalist bloggers have begun to levy rare criticism at Putin for failing to address the bridge attack, the Washington-based Institute for the Study of War noted. Abbas Gallyamov, an independent Russian political analyst and a former speechwriter for Putin, said the Russian president, had not responded forcefully enough to satisfy angry war hawks. “Because once again, they see that when the authorities say that everything is going according to plan and we’re winning, that they’re lying, and it demoralizes them,” he said. Putin personally opened the Kerch Bridge in May 2018 by driving a truck across it as a symbol of Moscow’s claims on Crimea. The bridge, the longest in Europe, is vital to sustaining Russia’s military operations in southern Ukraine. No one has yet claimed responsibility for damaging it.