The OSCE's top official for freedom of the press warned Friday of "rapidly deteriorating" climate for the media in Ukraine, and said further attacks could fuel conflict in the violence-torn country.

Dunja Mijatovic said her office had documented hundreds of cases of violence against the media, including murder, assault and kidnappings, since anti-government protests began in Kiev late last year.

The United States on Friday offered a cautious response to Russian President Vladimir Putin's statement that he would respect the result of Ukraine's weekend election.

"We would welcome an indication from Russia that they would accept the results of a free and fair and democratic election in Ukraine," said White House spokesman Jay Carney.

Russian President Vladimir Putin pledged Friday to respect the outcome of Ukraine's presidential election but warned that the country had descended into all-out civil war after a bloody upsurge in separatist violence.

At least seven people were killed in fighting between rebels and defense forces outside the eastern industrial hub of Donetsk on Friday, a day after the deaths of 18 soldiers in the heaviest loss for the Ukraine military since the conflict began.

At least five people were killed Friday in fighting near Ukraine's eastern hub of Donetsk two days before a presidential election undermined by an upsurge in attacks by pro-Russian separatists.

The latest bloodshed on the heels of the deaths of 18 soldiers Thursday in the eastern rustbelt near Russia underscores the trouble the interim leaders have in making sure they can pull off a safe and well-attended vote Sunday.

Russian Foreign Minister Sergei Lavrov said on Friday the West needed to learn the "right lesson" from the Ukraine crisis, as he criticized efforts to contain Russia since the collapse of the USSR.

"If the goal is to prevent such crises from repeating in the future, the right lesson must be learned from events in Ukraine," Lavrov told a security conference in Moscow. 

German Chancellor Angela Merkel on Friday called on Russian President Vladimir Putin to accept the OSCE's assessment on Ukrainian presidential elections this weekend.

"I expect Russia to respect the doubtlessly objective assessment of the OSCE -- after all it is a member of the organisation," Merkel told newspaper the Saarbruecker Zeitung.

Pro-Russian rebels firing mortar shells and grenades killed 14 Ukrainian soldiers on Thursday, the blackest day yet for the military and a dramatic ratcheting up of tensions just three days before a crunch election.

The attacks in the eastern industrial belt near the Russian border underscored the difficulties of the embattled Kiev government in resolving a crisis that is threatening to tear the country apart.

Russia's defense ministry said Thursday that four trains and more than a dozen planes had taken equipment and troops away from regions bordering Ukraine.

After President Vladimir Putin ordered the troops to return to bases, four trains loaded with arms and 15 Ilyushin-76 transport planes carrying troops departed from bases in the Rostov, Belgorod and Bryansk regions on Wednesday, the ministry said in a statement.

Thailand's deeply divided power blocs on Thursday resumed crisis talks ordered by the country's no-nonsense army chief, as supporters of the beleaguered government called for a national referendum on how to break a crippling political deadlock.

The opposing camps and other top political actors gathered at the bargaining table for the second straight day at a heavily guarded military social club in the capital Bangkok beginning at 2 pm (07:00 GMT). 

U.S. Vice President Joe Biden met Cyprus leaders Thursday to spur talks on ending their island's 40-year division and seek support for threatened sanctions against Russia.

After talks with President Nicos Anastasiades, the Greek Cypriot leader, and Turkish Cypriot counterpart Dervis Eroglu, Biden cautioned against overstating the role of the United States in reunification efforts.