Tony Blair has said he is confident of turning the tide of public opinion if war with Iraq becomes necessary.

The prime minister was speaking as it emerged empty chemical weapons warheads had been discovered by UN inspectors in southern Iraq.

We will use conflict if Saddam refuses to disarm himself properly Tony Blair

Even before the discovery - dismissed by Baghdad as a "storm in teacup" - Mr Blair was saying that finds in Iraq would turn the tide of public opinion.

"I believe as people hear the arguments and see the work of the inspectors in Iraq unfold, I think they will understand that reluctantly and as a last resort, we will use conflict if Saddam refuses to disarm himself properly," Mr Blair told Sky.

"I think those facts will alter people's thinking a lot."

The warheads - said to be in "excellent condition" - were found at the Ukhaider ammunition storage area.

HMS Ocean will carry Marines east

A Downing Street spokesman said Mr Blair, who is on a visit to Scotland, had been informed of the find.

Mr Blair has so far been reluctant to comment, but BBC political editor Andrew Marr said it was the evidence Mr Blair had been praying for and could prove "very significant" in his efforts to win over opponents in relation to Iraq.

It is likely Mr Blair is happy to wait until he meets Hans Blix at Chequers on Friday before making clear his position on the find.

But the find will be seen as significant particularly as the warheads were not listed in Iraq's 12,000-page dossier detailing its nuclear, chemical, biological and long-range missiles programmes.

Earlier a senior government source said that Saddam Hussein would be "making the mistake of his life" if he thought weapons inspectors had to find a "smoking gun" before he was in breach of UN resolutions.

Reporting back

Failure to comply fully with the inspectors would be enough, he told the BBC.

But he acknowledged the British people would be happier if a second UN resolution was implemented before any military action against Iraq.

UN inspectors are due to report on 27 January, although the government does not see that date as a hard deadline.

Chief weapons inspector Hans Blix - in Brussels for talks with senior EU officials - has said Iraq must do more to co-operate with the inspectors.

Foreign Secretary Jack Straw will meet his US counterpart Colin Powell next week to discuss the Iraq situation, ahead of a meeting between Mr Blair and President George Bush later this month.

Mr Blair's trip to Scotland is seen as part of a bid to win backing for his stance on Iraq.

The Scottish National Party challenged him to allow a Commons debate on the possibility of war - a debate the Scottish Parliament held on Thursday.

A majority of MSPs agreed that if Saddam Hussein failed to comply with the United Nations resolution, then the security council should meet again.

Unilateral action?

The prime minister is still refusing to rule out British military support for unilateral US action against Iraq.

And Labour Party chairman Dr John Reid insisted the cabinet was united on Iraq.

He reiterated the government's goal of disarming Saddam Hussein but said the aim was "to pursue the UN route".

Mr Blair's message is that future generations will be haunted by the consequences of weakness if the threat of Iraq's weapons is not confronted.

International Development Secretary Clare Short has said the UK should not back any action without a second UN resolution.

The prime minister instead said an "unreasonable or unilateral" block would not be allowed to confine other nations.

Britain dispatched fresh forces on Thursday, with the departure of the helicopter carrier HMS Ocean and Ark Royal.