Russia on Monday accused the European Union of putting pressure on Bulgaria to suspend work on a key Kremlin-backed gas pipeline and called eastward expansion by NATO was "counterproductive."

Foreign Minister Sergei Lavrov said Bulgaria's move to halt work on the South Stream gas pipeline suggested the EU was seeking revenge over the Ukraine crisis.

"It's unclear what they want from us. In my opinion, on Ukraine we are already doing everything that is necessary to calm down the situation," Lavrov said after talks with Finnish Foreign Minister Erkki Tuomioja.

"Sometimes Brussels is guided by a desire to punish, a desire to take revenge," Lavrov said, referring to the Belgian capital and headquarters of  EU.

Bulgaria is a member of the 28-nation European alliance.

"As far as EU policies over Russia are concerned, I don't think one can find any serious politicians who would call them constructive."

Lavrov also criticized NATO's decision last week to increase security in eastern Europe.

"An artificial attempt to continue NATO expansion to the east and any other direction, to continue moving military infrastructure closer towards the borders, including Russia's borders, is definitely counterproductive and contradicts the obligations which NATO country members have taken upon themselves," he said.

Russia's top diplomat said the EU should stop pressing Ukraine to choose between Russia and the West, saying all three parties should find a way to cooperate in a three-way format.