The Russian president's plan to use the meeting as a stage on which to demonstrate his international stature to a sceptical electorate was fast falling flat last night as a fierce domestic row broke out over Chechnya, and the International Monetary Fund (IMF) threatened to postpone payments in a $10bn loan.
The summit's agenda - what to do about the world's ageing power stations, lethal radioactive dumps, and poorly guarded fissile materials - was also sidelined by the tragedy in Lebanon, which produced a flurry of statements from the assembled leaders, calling for a ceasefire. Both Mr Yeltsin and President Bill Clinton dispatched their envoys to the region, while John Major - in between calling for an end to the ban on British beef - called for an "interim ceasefire" as a first step to peace.
Like a recurring fever, the Chechen war flared up again when the Communist- dominated lower house of parliament summoned Pavel Grachev, the Russian defence minister, to explain the death of at least 53 federal troops in a Chechen ambush on Tuesday - in a war that Mr Yeltsin claims has ended. The general offered to quit, prompting speculation that he is about to be fired, although his move was more of a gesture, as the president is the only official empowered to accept his resignation.
And Mr Yeltsin, in an unusual move, vowed to punish the responsible commanders. "The military leadership is to blame," he said. It was a rare attack on the military hardliners, and comes amid growing reports that they have been withholding information about the continuing hostilities in Chechnya.
Mr Yeltsin's problems were compounded still further by rumblings from the IMF that it may withhold at least one installation of the $10bn (pounds 6.5bn) loan it recently agreed to make to Russia, allowing the government to pay long-delayed wages and pensions.
An official said that the fund was "concerned by signs that Russia may be backing away from reforms". It was a clear warning that payments may be stopped if Russia fails to meet the strict fiscal conditions laid down by the IMF.
None of this fits into the plan that Mr Yeltsin must have had in mind when he invited the G7 to Moscow nearly a year ago. Yesterday, as the media gathered for the weekend meeting on a warm spring day, he said he was "fighting fit, despite his difficulties". But he seemed to have a surplus of the latter.
The G7 leaders, who last night attended at a lavish banquet in the Kremlin marking the summit's opening, have come to Moscow to discuss nuclear safety and security, but it is also a demonstration of Western support for Mr Yeltsin before June's presidential elections. They are keen to prevent a victory by the resurgent Communists, whom they believe could stop Russia's reforms dead in their tracks.
They are, however, usually careful not to admit as much in public. Asked whether he supported Mr Yeltsin's efforts to win a second term, Mr Major yesterday replied: "That is a matter for the Russian people. It would be impertinent for me to express a preference. We do have a strong view that the reform process is very important and wish to see it proceeding."