French Foreign Minister Jean-Yves Le Drian warned Monday that "all the elements" were in place for Russia to wage a "major offensive" against Ukraine after Moscow massed thousands of troops on its borders.

"Are there all the elements for a major offensive by Russian forces in Ukraine? Yes, there are. It's possible, it's possible quickly," Le Drian told France 5 television adding there was nothing to suggest Moscow had yet taken a decision.

The EU – alongside other Western allies – has vowed to impose massive sanctions on Moscow if it stages a further incursion into Ukraine.

The United States has warned that a Russian invasion of Ukraine could be imminent and their Western allies have threatened a crippling package of economic sanctions in response.

Russian Defence Minister Sergei Shoigu announced on Monday the end of some of Moscow's massive military drills in Russia and Belarus, though he told Russian President Vladimir Putin others were ongoing.

Earlier, Russian Foreign Minister Sergei Lavrov told Putin that there was a "chance" of reaching an agreement on security with the West in what appeared to be a possible climbdown amid the raging tensions.