KIEV - Russia on Saturday accused the West of seeking regime change in Moscow, raising tensions over the Ukraine conflict in the worst crisis in relations since the end of the Cold War.
Foreign Minister Sergei Lavrov spoke out against Western sanctions on Russia after US Vice President Joe Biden hinted Friday at possible further measures over Moscow's "unacceptable" role in the former Soviet republic.
Kiev's defence minister charged Saturday that there were 7,500 Russian troops in eastern Ukraine, although Russia denies claims that it provides military support to pro-Moscow separatists battling government forces.
"The West is showing unambiguously that they do not want to force (Russia) to change policy. They want to achieve a change of regime," Lavrov said in Moscow.
"Now public figures in Western countries are saying that it's necessary to introduce sanctions that would destroy the economy and rouse public protests," he added in comments cited by the state-run TASS news agency.
The United States and European Union have imposed several rounds of sanctions on Moscow over Ukraine, targeting the key energy, defence and finance sectors. As a result, the ruble has lost just under a third of its value against the euro since the start of the year.
In Kiev Friday, Biden accused Russia of failing to honour a peace agreement signed in September, which included a now tattered ceasefire for eastern Ukraine.
"So long as that continues, Russia will face rising costs, greater isolation," he added.
Some 4,300 people have been killed in the conflict in seven months, according to the United Nations, including 298 who died when Malaysia Airlines flight MH17 was shot down in July.
Nearly 1,000 people have died since the ceasefire came into effect.
NATO membership 'science fiction'
Lavrov's comments came after Ukraine's Defence Minister Stepan Poltorak claimed Russia had thousands of troops in the east and vowed that the cash-strapped country would boost its military capacity.
"The presence of 7,500 representatives of Russian armed forces in Ukraine destabilises the situation and prevents us from stabilising it," Poltorak said.
A European government source speaking on condition of anonymity put the number of Russian tanks in eastern Ukraine at 140, highlighting "pressure" on the port city of Mariupol.
Seizing Mariupol would be vital to any separatist plan to create a land corridor between the Russian border and Crimea, a region which Russia annexed from Ukraine earlier this year.
Ukrainian military spokesman Andriy Lysenko said it did not have clear figures to corroborate that number but pointed to the presence of a range of other military hardware as well.
Ukraine's new coalition declared Friday that joining NATO was a priority, stipulating that a law be passed by the end of the year confirming the intention to push for membership.
The five-party coalition, agreed on Friday after October elections, features the groupings of President Petro Poroshenko, Prime Minister Arseniy Yatsenyuk and former premier Yulia Tymoshenko.
But experts play down Ukraine's chances of joining NATO anytime soon.
"The idea of the alliance accepting a country in armed conflict with Russia is science fiction," said Vasyl Filipchuk, a former senior Ukrainian official who is chairman of the International Centre for Policy Studies in Kiev.
More unrest in east
NATO this week warned of a "very serious build-up" of Russian troops, artillery and air defence systems inside Ukraine and on the Russian side of the border.
In the latest batch of US assistance to Ukraine, three radars designed to detect incoming mortar fire were delivered Friday following Biden's visit, with a total of 20 arriving in the next few weeks.
The United States has so far ruled out providing weapons and ammunition to Ukraine, approving only "non-lethal" assistance such as radars, night vision goggles and body armour.
Ukraine's head of security operations in the east said that 20 units of Russian "military hardware" had crossed the border Saturday, adding that they were en route to the rebel stronghold of Lugansk.
In the past 24 hours, four Ukrainian soldiers and one civilian have been killed in eastern Ukraine, officials said.