Sharjah 24 - AFP: Ukrainian President Volodymyr Zelensky on Tuesday urged NATO to speed up his country's membership into the alliance, saying it was the only way to end fighting with pro-Russia separatists.

Zelensky spoke with NATO Secretary General Jens Stoltenberg after an increase in clashes and Russian military movements on the border raised fears of an escalation of the separatist conflict in eastern Ukraine.

In a tweet after the call, Zelensky said it was time for NATO to move forward with Ukraine's longstanding desire for membership.

He said Kiev was committed to defence reforms requested by the alliance in exchange for membership. 

"But reforms alone will not stop Russia," said Zelensky, whose government has said it hopes to be invited this year to join a NATO Membership Action Plan (MAP). 

"NATO is the only way to end the war in Donbas. Ukraine's MAP will be a real signal for Russia."

Fears have been mounting of a major escalation of the conflict in eastern Ukraine, where government forces have battled separatists in the mainly Russian-speaking Donbas region since 2014.

Ukraine last week accused Russia of massing thousands of military personnel on its northern and eastern borders as well as on the Crimean peninsula annexed by Moscow. 

The United States, the central power in NATO, stopped short of saying that Ukraine's membership had become more urgent and said Kiev must first complete reforms.

But he said President Joe Biden's administration supported the "open-door" policy of NATO and "the right of each sovereign country to choose for itself" whether to join the alliance.

Kiev's Western allies have rushed to its defence with a series of statements warning Russia against taking further action and seeking explanations for its troop buildup.