KYIV, Nov 26 (Reuters) - President Volodymyr Zelenskiy on Friday said Ukraine had uncovered a plot to overthrow his government next week, involving individuals from Russia caught on tape talking about roping Ukraine"s richest businessman into backing a coup. The Kremlin denied any role in any coup plot, and the businessman called the president"s account an "absolute lie." Zelenskiy himself gave few details and stopped short of saying whether he believed the Kremlin was behind the plot. But the accusation raised the temperature at a time when Kyiv and its Western allies have already accused Moscow of massing troops near the Ukrainian border for a possible assault, a suggestion Moscow dismisses as false and alarmist. Speaking at an hours-long news conference, Zelenskiy said Ukrainian intelligence had obtained audio recordings of the plotters talking about involving business magnate Rinat Akhmetov into joining their coup. "We have challenges not only from the Russian Federation and possible escalation - we have big internal challenges. I received information that a coup d"etat will take place in our country on Dec. 1-2," Zelenskiy said. Akhmetov said in a statement: "The information made public by Volodymyr Zelenskiy about attempts to draw me into some kind of coup is an absolute lie. I am outraged by the spread of this lie, no matter what the president"s motives are." "As a Ukrainian citizen, the country"s biggest investor, taxpayer, and employer, I will continue to defend a free Ukraine, a free economy, democracy, and freedom of speech." Ukraine"s sovereign dollar bonds tumbled to their lowest level in more than a year on Friday and the cost of insuring exposure to the country"s debt soared amid rising security concerns. UKRAINE PREPARED FOR ESCALATION Zelenskiy did not give full details of the coup plot. Asked explicitly whether he thought the Kremlin was involved, he said: "I"m sorry, I can"t talk about it." Ukrainian President Volodymyr Zelenskiy attends a news briefing following the Ukraine-EU summit in Kyiv, Ukraine October 12, 2021. REUTERS/Valentyn Ogirenko/File Photo Ukrainian President Volodymyr Zelenskiy attends a news briefing following the Ukraine-EU summit in Kyiv, Ukraine October 12, 2021. REUTERS/Valentyn Ogirenko/File Photo But he also spoke at length at the news conference of a threat of Russian military escalation, and said Ukraine would be ready for it. "We are in full control of our borders and are fully prepared for any escalation," Zelenskiy said. The head of Ukraine"s military intelligence told the Military Times outlet last week that Russia had more than 92,000 troops massed around Ukraine"s borders and was preparing for an attack by the end of January or beginning of February. Ukraine, which wants to join the NATO military alliance, has blamed Moscow for supporting separatists in a conflict in its east since 2014. It received a large consignment of U.S. ammunition and Javelin missiles earlier this year, prompting criticism from Russia. U.S. officials were in touch with Ukraine to get additional information on the plot, said Assistant Secretary of State for European and Eurasian Affairs Karen Donfried. Ministers from NATO member states, including U.S. top diplomat Antony Blinken, would also meet Ukrainian officials during a summit in Latvia next week, Donfried told reporters in a telephone briefing. Zelenskiy also said his chief of staff Andriy Yermak would soon be contacting representatives of Russia about the standoff between the two countries. Separately, Yermak said he would be contacting senior Kremlin official Dmitry Kozak. Russia has said it suspects Ukraine of wanting to recapture separatist-controlled territory by force. Zelenskiy said Ukraine had no such plans and added that Russia"s rhetoric opposing Ukraine"s bid to join NATO was a worrying signal. A former actor who once played a fictional president in a popular sitcom, the 43-year-old Zelenskiy came to power by a landslide in 2019 promising to end the war in eastern Ukraine, which Kyiv says has killed 14,000 people. But after a lull in fighting and confidence-building measures including prisoner swaps, tensions with Russia rose this year. President Vladimir Putin said the West was taking his "red lines" about NATO expansion too lightly. read more At his news conference, Zelenskiy said he wanted the prisoner swaps to resume. He called on Russia to state explicitly that it would not launch a new attack on Ukraine.