Supporters of radical Shiite Muslim loyal to Moqtada Sadr on Thursday declared holy war against foreign troops in Iraq after four of Sadr's followers were arrested in Basrah, south of Iraq.

"We will wage jihad (holy war) and war against the foreign troops," said Sheikh Saad al-Basri, Sadr's representative in the overwhelmingly Shiite city, in a statement.

Basri accused British forces of arresting four Sadr supporters in order to "create in Basrah the state of crisis that exists in Najaf," the statement said.

He said that the British troops breached its commitments that were reached with Iraq's Shiite parties and surrounded Sadr's main office in Basrah, some 550 km south of Baghdad.

It also arrested four of Sadr's followers there without charges, he added.