PRIME Minister Tony Blair issued a plea to so-called rogue states yesterday to give up their illicit weapons programmes.

In an apparent message to countries such as Iran and North Korea, Mr Blair told UK troops during a whistle-stop visit to Basra that last year's war in Iraq was a test case of how the international community deals with repressive regimes that wish to develop weapons of mass destruction (WMD).

Speaking to journalists later on his plane returning to Britain, he said he wanted to send out the message that there was an alternative way of dealing with WMD.

Although he did not mention any country by name, it was thought he was referring to Tehran and Pyongyang, whose nuclear ambitions have sparked international tension during recent months.

The Prime Minister repeated his belief that the issue of "rogue repressive states developing weapons of mass destruction" remained the major security threat of the 21st Century.

He said: "It's important to say to countries that may have engaged in such programmes: 'Look, there's a different way of dealing with this.'

"I believe, as strongly as I ever have, that this is the security threat and if we don't deal with it, we will rue the day we didn't."

In his surprise visit to Basra earlier in the day, Mr Blair thanked troops for their part in toppling dictator Saddam Hussein and told them they had fought in a noble and good cause.

He told them they were "pioneers of soldiering in the 21st Century", leading the way in tackling the twin threats of repressive states and terrorism motivated by "the virus of Islamic extremism that is a perversion of the true faith of Islam but is nonetheless incredibly dangerous".

He said that having won the war, the coalition had to win the peace by showing it could help the Iraqi people towards a democratic and prosperous future.

He renewed warnings that states that develop WMD were "a huge, huge liability for the whole security of the world".

Speaking only days ahead of the expected publication of the Hutton Report into the death of scientist Dr David Kelly, which is expected to raise questions about the decision to go to war, Mr Blair repeated his belief in the rightness of his cause.

"The conflict here was a conflict of enormous importance because Iraq was a test case," he said.

"Iraq was a country whose regime had a proven record of the use of weapons of mass destruction - not just their development - and a regime so abhorrent that literally hundreds of thousands of its citizens died in prison camps and from torture and repression.

"If we had backed away from that, we would never have been able to confront this threat in the other countries where it exists."

Asked later whether he still believed WMD would be found in Iraq, the Prime Minister told reporters: "The first thing is to wait for the Iraq Survey Group report.

"I don't believe that the intelligence we got was wrong. We have got to wait and see what their report turns up."

Meanwhile, Mr Blair's envoy to Iraq, Sir Jeremy Greenstock, warned that anti-US insurgency was getting more sophisticated.

Mr Blair said the coming months would be a vital period for the restoration of normality in Iraq.

"The important thing is to realise we are about to enter into a very critical six months," he told reporters.

"We have got to get on top of the security situation and we have got to manage the transition. Both of those things are going to be difficult.

"It's very important to show to people in Iraq that we are not walking away from this."

Earlier, Mr Blair joined troops from 20 Brigade for lunch at their headquarters in one of Saddam's former palaces, overlooking the Shatt-al-Arab waterway.

Meanwhile, Liberal Democrat leader Charles Kennedy, who opposed military action, warned Mr Blair that the British people's recognition of the armed forces' professionalism did not mean the Prime Minister would escape scrutiny of his decision to go to war when Lord Hutton reports.

And the party's foreign affairs spokesman, Menzies Campbell, said: "The Prime Minister was right to acknowledge the tremendous achievements of British forces in Iraq.

"But that doesn't answer the central question of whether we went to war on a false prospectus."

* An audiotape purported to be the voice of al Qaida leader Osama bin Laden cautioned Muslims against Middle East peace efforts and urged them instead to continue fighting for their religion.

The speaker, in the tape broadcast by Arab satellite channel Al Jazeera, called on Muslims to "continue the jihad (holy war) to check the conspiracies that are hatched against the Islamic nation"