KIEV, Aug. 24 - President Petro Poroshenko said on Monday Ukraine was facing a precarious year struggling to fend off what he called Russian strategies to undermine Kiev's drive for closer relations with Europe, Reuters reported.

He spoke at a ceremony in central Kiev to mark 24 years of Ukrainian independence from Moscow, its Soviet-era ruler, and then traveled to Berlin for talks with the leaders of France and Germany on the implementation of a much-violated ceasefire deal with pro-Russian rebels holding parts of eastern Ukraine.

"We have to get through the (coming) 25th year of independence as if on brittle ice. We must understand that the smallest misstep could be fatal. The war for Ukrainian independence is continuing," he said, addressing a crowd of several thousand.

At a news conference later in Berlin with Chancellor Angela Merkel and French President Francois Hollande, Poroshenko expressed his appreciation for their backing. "I'm extraordinarily thankful for the support and the efforts for de-escalation."

Merkel lamented that the ceasefire agreement was not being respected and said everything must be done to fully implement the broader peace deal reached in Minsk in February.

Earlier in Kiev, Poroshenko had said 50,000 Russian troops were massed along the Ukraine-Russia border and a further 9,000 were supporting pro-Russian rebels in separatist territories. New military convoys had been tracked crossing the border into Ukraine last week, he added.

While the threat of "full-scale military invasion" remains, Russia "also has an alternative strategy - to undermine the situation in the middle of our country and to put the country at loggerheads with key (foreign) partners, isolating it with the aggressor," he said.

Russian Foreign Minister Sergei Lavrov branded Poroshenko's comments as "unfounded and disgraceful", adding: "Their goal is to break the 'genetic code' ensuring the unity of our nations. I think he won't succeed in that."

Russia, which annexed Ukraine's Crimea peninsula last year after an uprising toppled a pro-Russian president in Kiev, has dismissed accusations by NATO and other powers that it has sent arms and troops to back separatists in the east.

Both sides have withdrawn large numbers of heavy weapons from the conflict zone in line with February's Minsk peace agreement, but clashes still take a steady toll of lives daily.

Lavrov reiterated that Russia wanted Germany and France to put pressure on Poroshenko to stick to Ukraine's commitments under the Minsk agreement and to grant the rebel regions greater autonomy. Russia says changes to the Ukrainian constitution to that end fall short of what had been agreed.

More than 6,500 people have been killed since fighting erupted in April 2014. (rt/ez)