Jack Straw has dismissed suggestions that coalition forces would "plant" weapons of mass destruction to justify the war in Iraq.
Straw: Saddam was skilled at hiding weapons
The UK foreign secretary said "immense care" would be taken to check the veracity of any weapons finds.
Mr Straw was speaking in a special edition of BBC News Interactive's phone-in programme Talking Point.
He admitted that justifying the war to the public would be easier if weapons of mass destruction - such as the unaccounted for 10,000 litres of anthrax - were found.
But he said finding such weapons was not the justification for military action.
Asked whether UN inspectors should now return to Iraq to verify any finds, he said chief inspector Hans Blix had already said it would not be right at present for him to go back to Iraq because it was a military situation where inspectors would be unable to work.
Why the devil would we plant any of this, because this military action was justified on the day that we took it
But Mr Straw said he recognised the importance of verifying the nature of any weapons finds.
He said: "Given the fact that it will be American and British military who will be first on to any site it will always be possible for those who opposed this military action to say 'oh well, they were planted'.
"Now, they won't be planted. We're going to immense care to ensure the veracity of the finds and why the devil would we plant any of this, because this military action was justified on the day that we took it.
"We didn't justify the military action by saying the justification is conditional.
"We said it is entirely justified within the terms of (UN resolution) 1441 and all the other resolutions against which the Saddam regime refused to co-operate going back 12 years."
He accepted that physical proof of unaccounted for weapons of mass destruction would make it easier to justify the war.
But he said: "I don't however think it will be like that because of the months of warning that the Saddam regime had and their undoubted skill at hiding that material."
He admitted that the task of finding weapons would be "difficult".
But he said there was no question that Saddam had possessed such weapons.
Asked about the current situation in Iraq, Mr Straw admitted more should have been done to secure hospitals from looters in the country.
But he said that over the next few weeks "a new Baghdad" would emerge with improved quality of life for the Iraqi people.
What's so frightening about a state which is Islamic? We are a country with a state religion - it doesn't mean we are not a democracy
The foreign secretary said he hoped it wouldn't be long before Iraq was stabilised and coalition forces would leave.
He said he was not concerned about the prospect of an Islamic state emerging out of the war, saying the future government of Iraq was for Iraqis to decide via the ballot box.
"What's so frightening about a state which is Islamic?," he said.
"We are a country with a state religion - it doesn't mean we are not a democracy."
Mr Straw said Saddam's regime could have continued for another 10 to 15 years if action had not been taken in Iraq.
He said he was optimistic that the country would "not go down the path of extremism".
"I believe that we can create a benign environment," he said.
The foreign secretary said it was now important to make progress on the "road map" for Middle East peace.
He said injustice to the Palestinians "feeds the rhetoric" of terrorists.
Seeking a settlement which created a Palestinian state alongside a secure Israel "would remove one of the main breeding grounds for terrorism but not its justification".
Mr Straw said he was also hopeful that removing Saddam "and encouraging the emergence of democracy could be an exemplar for the rest of the region".
He played down talk that Syria and Iran would now be targeted.
He said there was no threat to either country, but acknowledged that the UK and the US had a "different view" in terms of their approach to the two countries.
On international relations, he defended the UK's close links with the US.
And he said he hoped there could be a more "mature" view of the US in the rest of the world reciprocated by more US involvement in international institutions.
He said many people in the US found the position of some European countries on the war in Iraq "inexplicable".
And he cautioned the French against seeking to create a "separate pole in what is a uni-polar world" on areas such as military matters and displomacy.
Mr Straw said that could cause greater instability in the world.
He said: "It is very important that we both recognise the consequences of our actions."
The programme will be broadcast on World Service radio and World TV on Sunday, 27 April at 1400GMT/1500BST.