MOSCOW (AFP) - The leaders of Russia, Ukraine, France and Germany on Thursday held four-way talks over the crisis in eastern Ukraine during which breaches of the ceasefire were denounced.

"The four leaders called for the implementation of the full package of measures agreed in Minsk on February 12," including a full ceasefire, withdrawal of heavy weapons and the release of prisoners, the presidency said in a statement. "The breaches in the ceasefire seen in recent days were denounced," added the statement.

The statement also said that foreign ministers from the four countries would speak later Thursday to define how the ceasefire was being implemented.

Representatives from the Organisation for Security and Cooperation in Europe (OSCE) would meet the warring parties on the ground later Thursday to "quickly put in place" the measures agreed in Minsk, added the statement.

Only four days after coming into effect, the truce agreed in the Belarus capital Minsk is in tatters.

This week, pro-Russian rebels ignored the agreement and stormed a strategic town in eastern Ukraine that they had surrounded, forcing thousands of government troops to flee.

Ukraine and the West accuse Russia of cynically engaging in peace talks while covertly deploying soldiers and military assistance to the pro-Moscow separatists.

The Kremlin denies the allegation.