In recent years President Vladimir Putin has grown increasingly insistent that NATO is encroaching close to Russia's borders, and Moscow last week demanded "legal guarantees" that the US-led alliance halt its eastward expansion.

Gorbachev resigned as president of the Soviet Union on December 25, 1991, days after the leaders of Belarus, Russia and Ukraine said the USSR no longer existed.

"How can one count on equal relations with the United States and the West in such a position," Gorbachev told state news agency RIA Novosti on the eve of the anniversary of his resignation as the leader of the USSR.

He said there was a "triumphant mood in the West, especially in the United States" after the fall of the Soviet Union in 1991.