By Martin Plaut BBC News

New reports of the offer surfaced in Zimbabwe's Sunday Mirror newspaper and has also made headlines in London.

At the end of all this, we must have free and fair elections, which will then give the people of Zimbabwe an opportunity to elect their own government Morgan Tsvangirai

But there appears to be little new in the story, with Mr Tsvangirai telling the BBC he was first approached in December.

Then his reaction was one of considerable scepticism, and he put out a statement denouncing the plan.

He said that Britain and South Africa were forming what was termed an "unholy alliance" designed to "neutralise the sovereign wishes of the people of Zimbabwe".

"The cutting edge of the diabolical onslaught is supposed to come in the form of a summit between Robert Mugabe and myself," he said.

Now Mr Tsvangirai appears more conciliatory, but still very wary of attempts to get President Mugabe to step down.

Opposition blueprint

He was more willing to consider the process seriously when he spoke to the BBC on Monday, spelling out how he saw the approach.

"The process really is a three-pronged one," he said.

"One is that we - the Movement for Democratic Change (MDC) and Zanu-PF - agree that Mugabe has become such a liability that the nation cannot move forward, so he has to retire.

"Secondly, it means that, in terms of the constitution, within three months we must go to elections.

"In the end, we all know that the conditions are not ideal for conducting a free and fair election, so we need some time so that the [right] conditions are created, the constitution is amended and that normal political activity stops lawlessness and returns the country to some national confidence.

"The last part is that, at the end of all this, we must have free and fair elections, which will then give the people of Zimbabwe an opportunity to elect their own government."

Morgan Tsvangirai says he wants free and fair elections

The opposition fears that the latest moves are just an attempt to reduce pressure on the government.

The timing of the story is seen as important.

The English cricket team is due to decide whether to play in the country.

Later this month, the European Union is considering whether to renew sanctions against Zimbabwe.

The Commonwealth has to decide whether to continue suspending the country from its councils in March.

South Africa link

But analysts also point to another date to watch.

At the end of this month, South African President Thabo Mbeki is due to visit London.

Suggestions that President Mugabe should stand down are very much in line with South African thinking.

Zanu-PF has dismissed the story and the MDC says it is not party to an exit package for Mr Mugabe.

But the reports have been too persistent and too widespread to be simply rejected as a media invention.

Clearly talks have been taking place with the aim of ending the crisis in Zimbabwe. No-one has denied that fact.

The question, therefore, is whether the story appearing in a Harare paper is just an attempt to take the heat off the Mugabe government, or whether it is the first indication of real movement towards a settlement of the crisis in Zimbabwe.

Both explanations are plausible. Only time will tell which one is accurate.