Boris Yeltsin, who engineered the final collapse of the Soviet Union and pushed Russia to embrace democracy and a market economy as the country’s first post-Communist president, has died aged 76.

Kremlin spokesman Alexander Smirnov said Yeltsin died, but gave no cause of death or further information.

The Interfax news agency cited an unidentified medical source as saying he had died of heart failure.

Although Yeltsin was initially admired abroad for his defiance of the monolithic social system, many Russians will remember him mostly for presiding over the steep decline of their nation.

He was a contradictory figure, rocketing to popularity in the Communist era on pledges to fight corruption - but proving unable, or unwilling, to prevent the looting of state industry as it moved into private hands during his nine years as Russia’s first freely elected president.

He also led Russia into a humiliating war against separatist rebels in Chechnya that ended with Russia’s pullout.

Yeltsin, who suffered from severe heart problems during his time in office, resigned on New Year’s Eve 1999, several months before his term was to end.

Boris Yeltsin’s visits to Britain and Ireland mixed high politics with low farce.

The low point surely came on September 30 1994, when the then Irish prime minister Albert Reynolds was left standing on the runway at Shannon Airport, studying his wristwatch, as President Yeltsin conspicuously failed to emerge from his plane.

There was prolonged confusion and mounting embarrassment as Mr Reynolds, anxious to brief Mr Yeltsin on the developing Northern Ireland peace process, waited on the tarmac for 15 minutes.

But Mr Yeltsin, on a stop-off during a flight home to Moscow after talks with US President Bill Clinton, failed to leave his Ilyushin 62 jet.

An Irish Army battalion due to provide Mr Yeltsin with a guard of honour and a military band waiting to play the national anthems were stood down after it became clear he was not going to appear.

A puzzled Mr Reynolds had 30 minutes of talks with Russian deputy prime minister Oleg Soskovetz, who later reported that his leader had been "too tired after a 17-hour flight" across the Atlantic to see his Irish host.

When he arrived back in Moscow, Mr Yeltsin told reporters "I can tell you honestly, I just overslept."

Although Mr Reynolds insisted he did not feel he had been snubbed, commentators universally assumed that the vodka-loving Russian president’s non-appearance had been the upshot of heavy drinking, rather than illness or tiredness.

The Russian President’s fondness for drink was indulged by British Prime Minister John Major in September 1994 when, during a weekend of informal talks at Chequers, Mr Major and his wife Norma took Yeltsin and his wife Naina for a quick drink at the local pub, The Bernard Arms.

That the Russian President was not permanently absorbed by the intricacies of high level diplomacy was evident too in May 1998 when, while attending the G8 summit in Birmingham, he collected a set of talking Teletubby toys to take back to Moscow for his grandchildren.

But such incidents aside, the Russian President’s dealings with Britain did cover issues of great moment.

He also grasped opportunities to defrost the Anglo-Russian relationship which the Cold War had put into deep freeze.

On January 30, 1992 Yeltsin, making his first visit to Britain since becoming Russian President, Yeltsin announced that Russian missiles would henceforth be turned away from British targets.

Following four hours of talks with John Major, the two leaders agreed a 15-point declaration committing them to peaceful settlement of disputes, control of weapons of mass destruction and nuclear non-proliferation.

On November 9, 1992, following another set of talks at Downing Street, Mr Major and President Yeltsin signed a series of agreements - including the first friendship treaty between the two countries since 1766 - prompting Mr Major to declare: "We are consigning the Cold War to history."

Later the same day the Russian President made a symbolic visit to the heart of capitalism, London’s Stock Exchange.

The following day, President Yeltsin enjoyed a rare honour, being invited to address a joint session of both houses of Parliament. Lunching with the Queen at Buckingham Palace, President Yeltsin invited her to visit Russia.

In October 1994, the thaw in the relationship between Britain and President Yeltsin’s Russia was completed when the Queen finally accepted Yeltsin’s long--standing invitation to visit Moscow.

The visit put an end to more than seven decades of estrangement between the Kremlin and Europe’s royalty, over the murder in 1918 of Tsar Nicholas II and his wife and children, who were relatives of the British royal family.

Becoming the first British monarch to set foot in Russia since 1908, the Queen, accompanied by the Duke of Edinburgh, received the warmest of welcomes from her host.

President Yeltsin pulled out all the stops, including a glittering reception at the Kremlin and a visit to the Bolshoi ballet.

In October 1997, the good relations between Britain and Russia were cemented further when Tony Blair visited Moscow.

He was bear-hugged by the Russian leader who described Blair as "young, energetic, very vigorous and thrusting".

In turn, Mr Blair complimented Yeltsin on being one of the most "dynamic and capable" leaders in the world.

Today Mr Blair said: "It is with sadness that I learned of the death of former president Yeltsin.

"He was a remarkable man who saw the need for democratic and economic reform and, in defending it, played a vital role at a crucial time in Russia’s history."