BAGHDAD, Iraq (CNN) -- Recent tensions between Iraqi forces and the British military are threatening the upcoming constitutional referendum, the governor of Basra province warned Monday.British forces arrested 12 people in a raid last week, including three police officers in the southern Iraqi city of Basra. Among them was a police captain.Gov. Mohammed Al-Waili expressed concern over the British military's actions, saying the arrests have created "chaos among the people of Basra.""They are threatening the upcoming referendum," he said. Al-Waili said the British military should deal with his office on a more regular basis and let him know what troops in the region are doing, "for both the safety of the people and the British forces."Al-Waili has threatened to stop dealing with the British military, but he said he opened negotiations two days ago. (Full story)He said he expected an apology from the British forces for their conduct. He added that Iraqi Prime Minister Ibrahim Al-Jaafari and the Interior Ministry have sent a fact-finding delegation to Basra to probe recent events.In a statement Friday, the British military said it was concerned "that members of Basra police are involved in terrorism. We know that there are good people in the Iraqi police service, and the actions of the few should not be allowed to obscure that fact." The statement, issued by the commander of Britain's 12th Mechanized Brigade, said that "it is our right to protect ourselves and innocent citizens."Relations have been strained since late September when British troops staged a raid to free two British undercover soldiers who were being held first by police and then, according to British officials, by a militant group.Basra officials said the two men, dressed in civilian clothes, were arrested after they began firing on civilians. Al-Waili and other Basra officials have demanded an apology from the British over the raids.Iraqis are scheduled to go to the polls Saturday to vote on the country's draft constitution.The government announced over the weekend there would be a four-day national holiday ahead of the vote and that 70,000 Iraqi troops and police would provide security.About 152,000 American troops are in the country, according to the U.S. military.Iraqi police commandos killedTwo Iraqi police commandos were killed and eight others wounded Monday in roadside bomb explosions while on their way to provide security for an Arab League delegation.The attack occurred while the delegation was inside a mosque in western Baghdad. The Arab League group had been invited for a Ramadan iftar feast at the Muslim Scholars Association, a Sunni organization.Earlier, police and the U.S. military said two Iraqi policemen and a U.S. soldier were killed Monday in separate attacks in Baghdad.Gunmen opened fire on an Iraqi police convoy on a western Baghdad highway near the al-Adil neighborhood, killing two officers and wounding six others, Baghdad police said.Elsewhere in the capital, a car bomb exploded outside a checkpoint near the International Zone, killing a Task Force Baghdad soldier.Initial reports indicated an Iraqi soldier, an interpreter and an Iraqi civilian were wounded in the blast.The death brought the number of U.S. troops killed since the start of the Iraq war to 1,965.Gunmen also opened fire on civilians in the southern Baghdad neighborhood of Saydiya, killing two people and wounding one, police said.Other developmentsNajaf Gov. As'ad Abu Gilal survived an assassination attempt Monday when a bomb went off near his convoy on the main road south of Baghdad in the city of Mahmudiya, according to a Najaf police official. The official said the convoy came under small-arms fire after the explosion. A high-ranking Najaf police officer and another member of the police escorting the convoy were wounded.Iraqi national security adviser Mowaffaq al-Rubaie said a majority of Sunnis support the constitution despite the vocal opposition of many Sunni leaders. He said the constitution was a huge step forward for Iraq and that he thought that it would pass. (Full story)Former Iraqi dictator Saddam Hussein is scheduled to stand trial October 19 in the 1982 killings of Shiite Muslims in the village of Dujail that followed attempts by opponents to assassinate him. CNN's Arwa Damon, Enes Dulami and Mohammed Twfeeq contributed to this report.