The governor of Basra province has accused British forces of destabilising security following the arrest of 12 people over attacks against UK troops.
There have been violent anti-British protests in Basra
The men, some of whom are police officers, are still being questioned.
Governor Mohammed al-Waili said the British should have co-ordinated with him and with Iraqi security forces.
But the BBC's Caroline Hawley said the police force was thought to have been infiltrated by militiamen involved in attacks on troops.
Seven British soldiers have been killed in a spate of attacks involving roadside bombs since May.
A military spokesman told the BBC co-ordination would have been very difficult because the local council had issued orders to all policemen not to have any dealings with UK forces.
Co-operation between British forces and the Iraqi police broke down last month after two British soldiers who were believed to be working undercover, were arrested by Iraqi police.
British troops later used armoured vehicles in an attempt to free the pair, causing anger among locals in Basra.
The ensuing clashes saw armoured cars being surrounded by mobs and set on fire by petrol bombs.
The 12 detainees, some of whom are accused of supporting radical Shia cleric Moqtada Sadr, are thought to include the director of Basra's state-run electricity company Odai Awad.
Employees of the company are threatening a strike unless he is released within 24 hours.
Mr al-Waili told the Associated Press news agency: "The British troops are responsible for destabilising security in the province.
"Recent random raids and arrests conducted by British forces...should have been co-ordinated with the Iraqi security forces and the governor."
The governor's comments came as Liberal Democrat leader Charles Kennedy called on Prime Minister Tony Blair to bring British troops home, saying they were no longer part of the solution in Iraq, but part of the problem.
Mr Kennedy was applauded by delegates at the party's Scottish conference in Glenrothes, Fife, when he told them: "It's high time our troops began to come home, as simple as that."
But a Ministry of Defence spokesman: "The Iraqi government has asked us to be there and we have always said we will stay as long as the government judge we are required."