The United States warned Russia of further sanctions if it did not mellow down the tensions in eastern Ukraine.

John Kerry, U.S. Secretary of State, told Sergei Lavrov, Russian Foreign Minister that the country might face more sanctions if it did not try to ease the problems in Ukriane.

According to the officials, Kerry also spoke to Ukrainian Prime Minister Arseny Yatseniuk.

"With Foreign Minister Lavrov, the secretary expressed deep concern over the lack of positive Russian steps to de-escalate, cited mounting evidence that separatists continue to increase the number of buildings under occupation and take journalists and other civilians captive," the state official said, reports Reuters.

"He urged Russia to tone down escalatory rhetoric, engage diplomatically in the east with the OSCE and Ukrainian government, and issue public statements calling for those occupying buildings to disarm and stand down in exchange for amnesty," he added.

The state official also said that sanctions would be passed against Russia if it did not go forward in taking steps to implement last week's Geneva agreement.

The U.S. had earlier made it clear that Russia would be liable for increased sanctions if it failed to fulfil commitments laid out in the 17 April Geneva accord, according to BBC.

According to the agreement, Russia should immediately end violence in eastern Ukraine.

Russian Prime Minister Dmitry Medvedev told the Russian Parliament Tuesday that the government of Russia would be able to "minimise the consequences" of any further sanctions.

Washington announced that it would decide on additional sanctions if Russia did not implement the agreement in the coming days.