Mikhail Gorbachev, the last leader of the Soviet Union, who brought the Cold War to a peaceful end, has died in Moscow aged 91.

"Mikhail Sergeyevich Gorbachev died this evening after a serious and long illness," the Central Clinical Hospital in Moscow said, quoted by the Interfax, TASS and RIA Novosti news agencies.

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

He will be especially remembered in Malta for the historic meeting he had on a cruise ship in Marsaxlokk Bay with US President George Bush in December 1989. That meeting was credited with having ended the Cold War.

Gorbachev spent much of the past two decades on the political periphery, intermittently calling for the Kremlin and the White House to mend ties as tensions soared to Cold War levels since Russia annexed Crimea in 2014 and launched an offensive in Ukraine earlier this year.

Gorbachev spent the twilight years of his life in and out of hospital with increasingly fragile health and observed self-quarantine during the pandemic as a precaution against the coronavirus. 

Mikhail Gorbachev attends an event in Berlin in 2009.

Gorbachev was regarded fondly in the West, where he was affectionately referred to by the nickname Gorby and best known for defusing US-Soviet nuclear tensions in the 1980s as well as bringing Eastern Europe out from behind the Iron Curtain.

He won a Nobel Peace Prize in 1990 for negotiating a historic nuclear arms pact with US leader Ronald Reagan and his decision to withhold the Soviet army when the Berlin Wall fell a year earlier was seen as key to preserving Cold War peace.

Malta summit meeting

Gorbachev's meeting with US President George H. W. Bush in Malta in 1989, just a few weeks after the fall of the Berlin Wall, is known for its declaration to an end to the Cold War.

He was also championed in the West for spearheading reforms to achieve transparency and greater public discussion that hastened the breakup of the Soviet empire.

Strained Putin ties

The first Russian leader to live past the age of 90, he was congratulated by world leaders, including US President Joe Biden and former German chancellor Angela Merkel on his 90th birthday.

At home, Gorbachev remained a controversial figure and had a difficult relationship with Russian President Vladimir Putin.

Gorbachev with Eddie Fenech Adami in Malta in 1989.

For Putin and many Russians, the breakup of the Soviet Union was a tragedy, bringing with it a decade of mass poverty and a weakening of Russia's stature on the global stage.

Many Russians still look back fondly to the Soviet period, and Putin leans on its achievements to buttress Russia's claim to greatness and his own prestige.

As the USSR collapsed, Gorbachev was superseded by the younger Boris Yeltsin, who became post-Soviet Russia's first president. 

From then on, Gorbachev was relegated to the sidelines devoting himself to educational and humanitarian projects. 

He made a disastrous attempt to return to politics and ran for president in 1996 but received just 0.5 percent of the vote.

Over the years he saw many of his major achievements rolled back by Putin.

George Bush shares a joke with Soviet leader Mikhail Gorbachev on December 3, 1989 on board the Maxim Gorky off Malta.