Russia told the world not to underestimate the considerable risks of nuclear war that it said it wanted to reduce and warned that conventional Western weapons were legitimate targets in Ukraine, where battles raged in the east.

"The risks now are considerable," Foreign Minister Sergey Lavrov told Russia's state television according to a transcript of an interview on the ministry's website.

"I would not want to elevate those risks artificially. Many would like that. The danger is serious, real. And we must not underestimate it."