"There are somewhere around a thousand, but it may be more," Colonel Chris Vernon told reporters when asked the size of the irregular forces within the city.

"It's quite clear that elements of (the Iraqi army's) 51 brigade that we gave an opportunity to capitulate have pulled back inside," he added.

Vernon said that the British had no immediate plans to launch an all-out assault on the city but they were able to stage incursions on a regular basis.

"We are in and out as we see fit. We will go in, come out, and one day we will stay."

He denied that British troops were besieging Basra, saying that a passage in the northeast of the city over the Tigris river had been left "entirely open".

Vernon admitted that such a policy could allow Iraqis to attempt to move reinforcements but he added that "we have got eyes on that area".

British troops had received help from residents inside Basra who provided intelligence on members of the ruling Baath party, who have been declared the chief target, he said.

"They are telling us where the Baath party is meeting and within hours that meeting place will no longer exist."

Some 3,500 Iraqi prisoners of war were being held at a British detention centre around the southern port of Umm Qasr, including several senior military and Baath party officials, Vernon said.

"We have some pretty high ranking officers, senior military rank up to general, talking pretty freely and giving some pretty good intelligence."

WAR.WIRE