Cabinet shaken by Cook's latest stand against rush to war

It was probably the worst kept secret in British politics. But when Robin Cook gave Tony Blair a clear hint yesterday that he was ready to quit over Iraq, everyone around the coffin-shaped Cabinet table was struck by the gravity of the moment.

Colleagues listened in tense silence as the Leader of the House of Commons made an eloquent case for the vital need for a second UN resolution, in the process "putting down a marker", as one minister put it, for his own future.

Just over 90 minutes later, Mr Cook underlined his position in typically cryptic fashion with a series of veiled remarks at an extraordinary Business Questions in the Commons.

Mr Cook's warnings came as Clare Short, the International Development Secretary, said she had "no regrets" about her warning at the weekend that Mr Blair was being "reckless" over Iraq.

Earlier, Ms Short stressed again her own fears that military strikes could trigger a humanitarian crisis. In a written ministerial statement, she said there was a "serious risk" that the international community could fail to cope with the impact of war on Iraqi civilians.

Perhaps unsurprisingly, given her vitriolic radio interview on Sunday, Ms Short was relatively muted in her remarks at Cabinet when Mr Blair asked for individual views on the current crisis.

But when it was Mr Cook's turn, it was obvious his approach to potential resignation couldn't be more different.

Typically calm and measured, the man who was once touted as a possible Labour leader in the 1990s put a powerful case for the need for a fresh UN mandate.

Later, in the House of Commons, he carried on. Mixing dry wit with sombre assessments , he triggered laughter when he said he would "certainly consider" allowing Parliamentary time next week for any ministerial resignations.

When asked whether collective responsibility would be relaxed during the expected Commons debate on the second UN resolution, he said: "Collective cabinet responsibility will apply and will apply to all those who are in the Cabinet at the time of the debate."

That reply brought a collective "oooh" from Tory MPs who instantly spotted he was talking about himself and Ms Short.

Mr Cook said that a vote on a substantive motion, which would allow a rebel amendment opposing war, would be held "as soon as possible" after the Security Council proceedings concluded and before troops went into action.

"I attach the highest importance to this House having the opportunity to debate and vote on the matter before conflict," he said as a raft of Labour MPs got up to demand just that. "I for one would not for one moment suggest those who express those legitimate doubts and questions are themselves lacking in any support for British troops."

As far back as last year, when it emerged Mr Cook wanted to restrict British support for the US to use Diego Garcia airbase, he has been seen as a possible leader of a rebellion. He insisted on the recall of Parliament last September and a cabinet discussion on the issue. There has been talk of his sacking in a reshuffle ever since Mr Blair scuppered his plans for an elected House of Lords earlier this year.