BAGHDAD, (Reuters) – A suicide bomber exploded a belt packed with explosives at a recruiting station for neighbourhood patrols in Iraq’s restive Diyala province on Thursday, killing 13 volunteers and wounding 10, police said.

Police said U.S. forces may have also been among the casualties in the attack that took place in Kanaan, 20 km (12 miles) southeast of Baquba, the province’s capital north of Baghdad.

A spokesman for U.S. forces confirmed an incident had taken place there but said he did not have any details. The police said the casualty toll could rise.

Mainly Sunni-Arab neighbourhood patrols have joined U.S. forces to fight against al Qaeda militants, one of the tactics Washington says has led to a 60 percent drop in attacks in Iraq since June. But the patrols have increasingly been targeted by militants, especially in provinces north of Baghdad, where U.S. commanders say al Qaeda has regrouped after being pushed out of other parts of Iraq.

U.S. commanders said they had found a torture chamber in Diyala province with chains on the walls and a battery connected to an iron bed, describing it as proof of al Qaeda’s activity in the area.

One of the other main factors U.S. commanders also credit for the decline in violence is a ceasefire by followers of the Shi’ite Muslim cleric Moqtada al-Sadr.

In a development welcomed by U.S. forces, Sadr’s spokesman said the cleric was considering extending the six-month truce after it expires in February.

Sadr, who led uprisings against U.S. troops in 2004 and whose militia was later described by U.S. commanders as their greatest threat, surprised both Iraqis and U.S. forces when he ordered a six-month freeze on his militia in August. “Yes, there is a chance that the freeze on the Mehdi Army will be extended,” spokesman Salah al-Ubaidy told Reuters late on Wednesday in Najaf, the holy Shi’ite city where the cleric’s followers are based.

U.S. spokesman Rear Admiral Greg Smith said: “Absolutely, we welcome the potential for the extension of the freeze. “We believe that al-Sayyed Moqtada al Sadr’s pledge to work in a political process and the peaceful transition is much more constructive than through violence,” he said, using an honorific title for a man Washington tried to arrest in 2004.

The son of a revered Shi’ite cleric slain under Saddam Hussein, Sadr has wide influence in the Shi’ite south and parts of Baghdad although he does not himself hold high clerical rank. His movement says he has recently begun taking advanced Islamic studies in a bid to climb the ranks of the Shi’ite religious hierarchy and increase his influence while also earning more respect from current religious elders.

Elsewhere in the mainly Shi’ite south, the Interior Ministry named a replacement for the police chief of Babel province, Qais al-Mamouri, who was killed by a roadside bomb earlier this month after being praised by U.S. commanders for tackling militias.