NATO's chief has dismissed as "nonsense" a claim by Russia's President Vladimir Putin that the Ukrainian army operates as a "foreign legion" for the alliance.
NATO Secretary General Jens Stoltenberg also called on Russia to stop providing military support to pro-Russian rebels, BBC reported.
Putin said Ukraine's military was operating against Ukrainian national interests by seeking to contain Russia.
Violence in eastern Ukraine is at its worst level for months, with a series of deadly attacks over the past week.
The military said early Monday that seven Ukrainian soldiers had been killed fighting Russian-backed separatists in 24 hours.
On Saturday, a series of rocket attacks left 30 people dead and many more injured in the Black Sea city of Mariupol.
NATO and Ukrainian officials were meeting in Brussels to discuss the recent surge in fighting.
"The statement that there is a NATO legion in Ukraine is nonsense," Stoltenberg said. "There is no NATO legion, the foreign forces in Ukraine are Russian."
He was responding to comments that Putin made to students in St Petersburg.
"In effect, it is no longer an army but a foreign legion, in this case NATO's foreign legion, which does not of course pursue the aims of Ukraine's national interests," said the Russian president.
Those aims were "connected with achieving the geopolitical objectives of containing Russia", he said.
