Robert Mugabe

Commonwealth leaders are deciding their next move after Zimbabwe's decision to quit the organisation "with immediate effect".

The move follows a weekend of intense negotiations by Tony Blair at the Commonwealth summit in Abuja, Nigeria.

The prime minister headed off an attempt to get Zimbabwe readmitted but failed to get signs of change from the Mugabe regime.

The issue had split the assembled heads of government, with South Africa initially vetoing the continued suspension of its African neighbour.

Before heading home the prime minister defended the decision not to allow back Zimbabwe while its ailing regime, which has rigged elections and carried out human rights abuses, was still in charge.

Blair argued there was "no possible justification'' for lifting Zimbabwe's suspension from the 54-nation group, imposed a year ago.

"There is no doubt what the feeling of the Commonwealth is," he said.

"At the end, it was the right outcome and while it was tough getting there, I think it is important for the Commonwealth to send a strong signal.

"By maintaining the suspension, we have done that and it is now up to the Zimbabwe government to take the decision to bring themselves back into compliance with the principles set out by the Commonwealth."

In London, shadow foreign secretary Michael Ancram said the Commonwealth had passed a turning point.

"If the Commonwealth had given way and readmitted Robert Mugabe they would effectively have been turning a blind eye on all the principles that are the reason the Commonwealth exists,'' he said.

"For two years we have been told by Tony Blair and President Mbeke that quiet diplomacy was the way forward.

"Quiet diplomacy hasn't worked - now we have got to play much harder ball than we have up till now and I hope the international community will realise that.''

Liberal Democrat foreign affairs spokesman Menzies Campbell said Zimbabwe's decision would not spell the end of the Commonwealth.

"The Commonwealth, as we have found in the past, is bigger than any one member. Mr Mugabe was given chance after chance to bring his government in line with the principles of the Commonwealth itself, as set out in the Harare Declaration," he said.

"In the end, his defiance proved his undoing. The people who will suffer most are the citizens of Zimbabwe."

Zimbabwe reacted to the Commonwealth's verdict on readmission with characteristic defiance.

"Anything you agree on Zimbabwe which is short of this position, no matter how sweetly worded, means Zimbabwe is still a subject of the Commonwealth. This is unacceptable. It's quits, and quits it will be," said a statement from Harare.