Russia and the United States gave no sign of narrowing their differences on Ukraine and wider European security in talks in Geneva on Monday, as Moscow repeated demands that Washington says it cannot accept.

Russia has massed troops near Ukraine's border and demanded the U.S.-led NATO alliance rule out admitting the former Soviet state or expanding further into what Moscow sees as its back yard.

"Unfortunately we have a great disparity in our principled approaches to this. The U.S. and Russia in some ways have opposite views on what needs to be done," Russian Deputy Foreign Minister Sergei Ryabkov told a news conference.