More than 1,000 British and Danish troops , backed by tanks, helicopters and boats, arrested five supporters of Muqtada al-Sadr yesterday in the biggest attack mounted by Allied forces in Basra since the Iraq invasion three years ago.
Forces using 14 main battle tanks, Warrior armoured vehicles, and amphibious craft mounted a night raid on houses in five areas near the Shatt al-Arab waterway where four British troops were killed last month on a river patrol.
As amphibious landings took place, about 800 British troops and 200 Danish troops fought Iraqis who were using small arms fire, rocket-propelled grenades and a roadside bomb.
There were no coalition or civilian casualties after yesterday's operation, in which the British troops came under heavy fire as they crossed a bridge, said Major Charlie Burbridge, the spokesman for the Allied forces in southern Iraq.
The attack took place as US troops mounted an assault on alleged al-Qa'ida strongholds near Baghdad, killing 20 insurgents, including two women.
The Ministry of Defence said the Anglo-Danish operation - codenamed Pisa - had targeted a rogue group of militia who had been carrying out killings and kidnappings. Officers said they were operating on "very good intelligence".
An arms cache was found in one of the houses which included Katyusha rockets, roadside bombs, rifles and rocket-propelled grenades. The soldiers also found plastic explosive and fuses, as well as photographs of the militia they were seeking. They took away computers and will scour them for information.
The five Iraqis who were detained were described by army commanders as members of "a rogue, breakaway element" of one of the many Shia militias operating in the area.
"They've just found pictures of Muqtada al-Sadr in here which shows their sympathies," said Lieutenant Chris Pickles of C Company, 1 Yorks, who took part in the combined raid.
Danish soldiers advanced from the north, while the British, in armoured vehicles, arrived from the south, Major Burbridge said.
Other British forces reached the area on boats travelling to the junction of the Garmat Ali river and the Shatt al-Arab waterway in the operation that was supported by helicopters and jets.
The Defence Secretary, Des Browne, said yesterday: "The criminal gangs who target the people of Basra without discrimination are the scourge of the city. They stand in the way of democracy and progress. This was a daring yet vital series of raids, and my wholehearted thanks are extended to the brave men and women who pulled it off so successfully."
But as Mr Browne hailed the success of the operation, a former minister, the Labour MP Doug Henderson, called for the immediate withdrawal of British troops from Basra. "I would have thought that if the Americans in Baghdad have the situation that we have in Basra they'd be withdrawing now," he said in a GMTV interview to be screened tomorrow. "I think we should now come to an agreement with the Americans that the withdrawal should start to take place in Basra right away."
Tony Blair made it clear there would be no rapid pull-out from Basra in spite of raised expectations that the withdrawals could start in the spring as areas were handed over to the Iraqi government forces.
He told ABC News in America: "I think we've got to plan to succeed. If we start saying to the people we're fighting in Iraq we're ready to get out, irrespective of the success of the mission, I think that would be very serious for us."
Mr Blair said this week's Iraq Study Group report "gives us the right foundation to move forward". His remarks fuelled demands for Mr Blair to make a full statement to the Commons on Monday on the report which could signal a change of policy on the Middle East.
The Iraq Study Group, chaired by James Baker, the former US secretary of state, tackled the sensitive subject of the militias whose charismatic leaders were challenging the authority of the Iraqi government.
The report sanctioned the use of force "to stop militias that act as death squads or use violence against institutions of the state'' but it warned that solving the problem of the militias "requires national reconciliation".