The Kremlin says the leaders of pro-Russian breakaway regions in eastern Ukraine have asked President Vladimir Putin to help in "repelling the aggression" by Ukrainian armed forces and prevent a humanitarian disaster.

Kremlin spokesperson Dmitry Peskov announced on Wednesday that Putin received letters from the leaders of the self-proclaimed republics of Donetsk and Luhansk. These regions are controlled by separatists.

Peskov quoted the letters as saying, "Kiev is receiving comprehensive support, including military one, from the United States and other Western states. The Kiev regime is determined to resolve the conflict by force."

The spokesman said the letters ask Putin to help in accordance with the friendship, cooperation and mutual assistance treaties between Russia and the regions.

Earlier this week Putin recognized the two regions as independent states. He is poised to send in Russian troops in the name of providing "peacekeepers".