In an outspoken attack on the possible consequences of war in the Middle East, Charles Kennedy has warned that hundreds of thousands of people could die.

The Liberal Democrat leader has been a critic of the push for war with Iraq, arguing that the United Nations weapons inspectors should be given more time to do their job.

The party's MPs voted with Labour and Conservative rebels after last week's Commons debate on the government's handling of the Iraq crisis.

And speaking to the BBC on Sunday, Kennedy stepped up his attack on the government.

With Britain and America pushing for a second security council resolution authorising the use of military force, the Lib Dem leader said all other options should be exhausted first.

"Are we really arguing at this stage, before the UN process is complete, that the best thing to do is to start slaughtering people in their thousands, perhaps hundreds of thousands, as well as losing British and American and Australian lives in the process?" he asked. "I don't think so."

Speaking on BBC1's The Politics Show, he said it was "precipitate" to push for a second resolution and warned that his party may not support the use of force even if it does gain UN approval.

"If Dr Blix in due course comes back and says that the weapons inspectorate have now exhausted their course, that there are material breaches, there is substantial evidence of non-co-operation and they can't make further progress, the UN would then have to take a considered and serious view which would lead to a second resolution.

"In that context, I think it would be very hard indeed for a pro-UN party like the Liberal Democrats not to back it," added Kennedy.

The Lib Dem chief also took a swipe at the prime minister's comparisons between government critics on Iraq and the appeasers of Nazi Germany in the 1930s.

"I don't think that using words like appeasement in this context is appropriate. They just inflame the situation unnecessarily," said Kennedy.

"In the late 1930s, Hitler was steadily invading other countries and the appeasers were not willing to challenge him. The last time Saddam Hussein invaded a sovereign state - Kuwait - we as a party and the country as a whole supported the international action that was taken.

"Iraq is not in a position at this stage with all the diplomatic, military and weapons inspectorate pressure, to be having excursions to try to invade other countries, so the comparison doesn't stack."