Chris Smith has warned that even more Labour MPs would be prepared to vote against the government if it goes to war without a second United Nations resolution.

The former Cabinet minister, who led last week's backbench rebellion against the government, predicted that more than 121 Labour MPs would be prepared to defy the government in such circumstances.

Smith, who has been leading the calls for weapons inspectors to be given more time, said that MPs would be "very unhappy" with such a course of action.

But he claimed that the prime minister had already made up his mind to back any military action launched by the US.

He added that some Cabinet ministers were unhappy at the government's policy.

"I know that one or two of them certainly are already voicing to him [Tony Blair] directly their concerns and I hope they'll carry on doing so," Smith told GMTV's Sunday Programme.

However, Tony Blair's leadership was "not an issue" for those rebelling against his policy, he said.

While Labour rebels have warned of their unease at the government's policy, one senior minister has said that the Cabinet remains "absolutely rock solid" behind the prime minister.

Welsh Secretary Peter Hain said every minister was putting their position "on the line" to back Tony Blair.

"I think this is a matter of the whole government being on the line," he told the Sunday Telegraph.

"It is not a matter of the prime minister being on the line. I am in this just as every other member of the Cabinet. We are absolutely rock solid behind the prime minister.

"The more people who understand that both the prime minister and the whole of the government are putting ourselves on the line on this, the more people will begin to appreciate what is at stake here."

But the latest polling evidence suggests the public continue to back the rebels rather than the government.

A YouGov poll for the Mail on Sunday found that 58 per cent said they backed the pleas for continued inspections, while 34 per cent did not.