An explosion at the entrance to a logistics base in British-controlled southern Iraq wounded five British soldiers and several Iraqi civilians on Thursday, the British military said in an emailed statement.
The attack occurred during the afternoon at an entrance to the Shaibah logistics base west of Basra, Iraq's second largest city, in the far south of Iraq.
The British army said that it was not yet clear what caused the explosion.
A group led by al-Qaeda ally Abu Musab al-Zarqawi said in an Internet statement it was behind what it called a suicide attack to avenge alleged abuse by British soldiers of Iraqi prisoners.
"Three lions from the martyrs' brigade of al-Qaeda Organisation of Holy War in Iraq attacked the base for British occupation forces in Shaibah area in Basra. This operation is in response to the harm inflicted by British occupation forces on our brothers in prison," the statement said.
The group, which has claimed some of the deadliest attacks in Iraq, vowed in the statement to continue its attacks.
Three British soldiers, Corporal Daniel Kenyon and lance corporals Darren Larkin and Mark Cooley, are accused of abusing Iraqi detainees and face a variety of charges including battery, indecency and disgraceful conduct.
Photos which emerged during their military trial on Tuesday showed naked Iraqi men apparently forced to simulate sex and evoked the scandal involving US soldiers at Baghdad's Abu Ghraib prison.
Attacks on British bases in Basra are common, with insurgents frequently firing mortars at camps in the city. Britain has around 9,000 troops based in southern Iraq, mostly in Basra, where many Iraqi civilians are employed at the British military's bases.