Biden calls Gorbachev 'rare leader' who made world safer

US President Joe Biden on Tuesday hailed former Soviet leader Mikhail Gorbachev, who passed away in Moscow aged 91, as a "rare leader" who made the world a safer place.

"These were the acts of a rare leader - one with the imagination to see that a different future was possible and the courage to risk his entire career to achieve it," Biden said in a statement, referring to Gorbachev's democratic reforms. "The result was a safer world and greater freedom for millions of people."

"Mikhail Gorbachev was a man of remarkable vision," Biden added.

Gorbachev's death was announced on Tuesday by Russian news agencies, who said Gorbachev had died at a central hospital in Moscow "after a serious and long illness".

Gorbachev, in power between 1985 and 1991, helped bring US-Soviet relations out of a deep freeze and was the last surviving Cold War leader.

His life was one of the most influential of his times, and his reforms as Soviet leader transformed his country and allowed Eastern Europe to free itself from Soviet rule.

Other prominent US figures also weighed in on Gorbachev's legacy Tuesday.

"History will remember Mikhail Gorbachev as a giant who steered his great nation towards democracy," said former US Secretary of State James Baker III, who negotiated with Gorbachev in the final years of the Cold War. "He played a critical role in the peaceful conclusion of the Cold War by his decision against using force to hold the empire together ... The free world misses him greatly."

In a statement on Twitter, the Reagan Institute described Gorbachev as "a man who once was a political adversary of Ronald Reagan's who ended up becoming a friend."