Government forces and pro-Russian separatists exchanged fire near the city of Donetsk on Monday, as officials reported that at least 12 people had died in fighting despite a cease-fire declared earlier this month.
The Donetsk city council reported Monday that a battle was ongoing in the vicinity of the Donetsk airport.
A military spokesman said that seven Ukrainian servicemen were killed near the airport when their armored personnel carrier was hit by a shell fired by separatists. He said nine soldiers had been killed and 27 wounded in attacks during the preceding 24 hours.
Officials in Donetsk said at least three civilians were killed in the rebel-controlled city on Sunday.
It was the highest number of casualties reported since the cease-fire took effect on September 5.
At least 3,500 people have been killed since the fighting began in April, according to United Nations estimates.
Meanwhile, the Kremlin has opened an investigation into what it calls a Ukrainian genocide against Russian speakers in the east.
A body called the Investigative Committee accuses Ukraine's military of killing 2,500 people and destroying hundreds of buildings in Donetsk and Luhansk.
Ukraine has not commented.
'Far from satisfactory'
German Chancellor Angela Merkel on Monday called the situation in eastern Ukraine "far from satisfactory," stating that the current status of the cease-fire there and the future status of the rebel-controlled areas remain unclear, while there is no protection of or control over the Russian-Ukrainian border in those areas.
Resolving these issues, Merkel said, are "minimum requirements" for lifting the sanctions imposed on Moscow for its actions in Ukraine.
Meanwhile, France and Germany have offered to supply drones as part of efforts by the Organization for Security and Cooperation (OSCE) to beef up monitoring of the cease-fire in Ukraine, France's Foreign Ministry said on Monday.
More claims direct Russian involvement
More claims seem to be emerging putting Russian soldiers in the conflict zone in eastern Ukraine.
According to Reuters, two Ukrainian servicemen captured and since released by who they initially thought were separatist rebels, have said that their captors were in fact regular Russian troops.
“They said they were [members of an] an airborne assault battalion from Kostroma,” said Oleksiy Koshelenko, one of the captured Ukrainian soldiers, referring to a city 300 kilometers northeast of Moscow.
The other Ukrainian soldier, Andriy Krupa, made a similar statement.
Both said they were captured August 24-25 near the town of Ilovaysk and freed after a month in captivity. On August 26, Ukraine released a video of 10 Russian paratroopers captured in the same area with one of them saying his regiment was based in Kostroma.
Moscow has consistently denied any direct involvement in the conflict in eastern Ukraine. It did admit that its soldiers had once crossed into Ukraine accidentally and that some soldiers might be supporting the rebellion on their own time.
Lenin statue toppled
In another development, residents in the eastern city of Kharkiv have felled one of its most prominent Russian symbols - a statue of Soviet icon Vladimir Lenin.
Groups of men scrambled onto the monument in the center square Sunday and carved the words "Glory to Ukraine" on it before sawing off the legs and pulling it down with cables.
Thousands of demonstrators cheered and rushed to grab parts of the dismantled statue for souvenirs. Police did not intervene.
More than 160 Lenin monuments have toppled in Ukraine in less than a year.
Also Sunday, President Barack Obama said on CBS television's 60 Minutes program that he thinks there is a possibility Russia will move in a "better direction."
He noted that such progress in Ukraine - including a cease-fire with the separatists, a gas deal with Moscow and sanctions that have hurt the Russian economy - would not have happened without a firm line from the U.S. that also gives Russia the chance to take a different path.
Some material for this report came from Reuters.