Ukrainian President Petro Poroshenko called on NATO states to send weapons to his country, saying in a newspaper interview that civilian deaths and the growing conflict should provide the Western alliance with enough reason to come to Ukraine's aid.

The United States is reconsidering whether to provide weapons to Ukraine in its fight against Russian-backed separatists, senior administration officials said on Monday, but added that no decision had been made.

"The escalation of the conflict that's happening today, the increasing number of civilian casualties, especially after the terrorist attacks in Volnovakha and Donetsk as well as the bombardment of Mariupol... should move the alliance to provide Ukraine with more support," Poroshenko said in an advance copy of an interview to be published in Germany's Die Welt on Thursday.

"(That) includes, among other things, delivering modern weapons for protection and for resisting the aggressor," Poroshenko said.

Poroshenko stressed that Ukraine wanted peace but that even peace must be defended so Kiev needed a strong army and new, modern weapons.

Asked what he expected from the West, Poroshenko said: "We still need a lot of military, technical and specialist help to improve the fighting strength of the Ukrainian army in its resistance of Russian aggression."

He said the International Monetary Fund (IMF) was considering replacing Ukraine's stand-by program with an Extended Fund Facility (EFF).

"We expect a positive decision soon as well as the possibility to get extra support from the European Union and other partners," Poroshenko said.