Ukrainian soldiers withdrew their 82mm mortars from two villages near the ruins of Donetsk airport on Saturday as a confidence building exercise aimed at winding down the conflict as diplomat efforts continue.

"The fact that we are withdrawing weapons of up to 100mm is evidence that we are in compliance with the Minsk agreement," the Ukrainian military said in a statement.

In case of a crisis, Ukrainian troops will be ready to be redeployed in the shortest possible time, the statement added.

Kyiv's withdrawal came after pro-Russian fighters said they had withdrawn light arms from the area on Thursday, in line with the September 1 Minsk agreement that negotiated a ceasefire.

The Organization for Security and Cooperation in Europe's chief monitor, Ertugrul Apakan, said this week that the ceasefire had been "largely holding" but that the situation remains "volatile."

Watch video 01:16 Poroshenko "fully co-operating" with OECD

The plan also calls for the creation of a 30-kilometer to 40-kilometer (18-25-mile) buffer zone between the warring parties. A similar withdrawal was completed last month in the separatist-held Lugansk region.

Shelling, recriminations continue

Meanwhile, both sides continue to accuse each other of violating the ceasefire agreement. The Ukrainian government said four soldiers were wounded by a landmine and accused rebels of having fired on army positions around Donestk.

In turn, the separatists said militias loyal to the central Ukrainian government had fired rockets at Donetsk.

"Ukrainian volunteer battalions are bombing Donetsk in order to derail the Minsk (peace) agreement and to provoke a response from us," the separatists' defense ministry spokesman Eduard Bassurin said.

Despite these setbacks, the United States said it is pleased with progress in de-escalating the bloodiest European conflict since the disintegration of Yugoslavia in the 1990s.

"We are now starting to see for the first time some pullback of Russian and separatist weapons," Assistant Secretary of State Victoria Nuland told a hearing in the US House of Representatives.

Russia denies backing separatists in eastern Ukraine in battles that began following last year's ouster of a pro-Moscow government after waves of protests over whether Ukraine would move westward or back into Moscow's orbit.

jar/sms (AFP, Reuters, Interfax)