Mr Peres should put firm pressure on Mr Sharon

Yesterday's decision by the Israeli Prime Minister Ariel Sharon to invite his Labour party rival Shimon Peres into talks on a unity government is welcome news

Yesterday's decision by the Israeli Prime Minister Ariel Sharon to invite his Labour party rival Shimon Peres into talks on a unity government is welcome news. Labour has agreed to shore up Mr Sharon's shaky coalition following the acceptance by Mr Sharon's cabinet of his Gaza withdrawal plan, and the unmourned departure of the two pro-settler ministers who had vetoed it.

The prospect of disengagement from Gaza - rejected by Mr Sharon's own Likud party two months ago - signals that the political establishment is moving closer to majority Israeli public opinion. At the same time, the extremists and hardliners who cling so desperately to the status quo are being isolated.

But there are still disturbing questions about the Sharon plan and - by extension - Mr Peres's decision to engage with it. Is military withdrawal, and the dismantlement of Jewish settlements in Gaza, a first step towards peace based upon a just and lasting settlement? Or is it just a step towards the unilateral enforcement of peace on Mr Sharon's terms?

The invitation to talks comes in the wake of the International Court of Justice's ruling last week that Mr Sharon's construction of a wall in the West Bank is illegal. This ruling served to underline the lack of progress on the West Bank, where only four isolated settlements are being removed by Mr Sharon. As a result, it is hard to avoid the impression that Mr Sharon is merely co-opting Mr Peres into an attempt to annex most of the West Bank settlements into an enlarged state.

Mr Peres is a Nobel peace laureate, but he is also a man whose political skills and judgement have been shown up in the past. He is, however, the one Israeli political figure who should recognise the dangers of diplomatic isolation arising from the moral defeat of the ICJ ruling. Now he has an opportunity to exert leverage for a quicker withdrawal from Gaza, a full disengagement from the West Bank, the re-routing of the separation fence, and the resumption of talks with the Palestinian leadership. The 80-year-old former prime minister is known to want a return to power and a senior portfolio in a new government. But he must not sell himself short.