LAHORE, Pakistan >> A judge ruled Thursday that police can keep holding a U.S. Embassy employee accused of killing two Pakistanis for at least eight more days, officials said — the latest development in a case that has heightened tensions between the U.S. and Pakistan.

The U.S. says the American, identified by Pakistanis as Raymond Allen Davis, has diplomatic immunity and that Pakistan must free him. U.S. officials say he shot the two Pakistanis in the city of Lahore because they were trying to rob him.

Pakistani authorities have avoided definitive statements on Davis’ level of diplomatic clearance, and have said the decision on his fate is up to the courts. Another judge, meanwhile, has instructed that the American be placed on the “exit control list” so that he cannot leave Pakistan.

If Davis is freed, it could spark backlash in a country that is a key counterterrorism ally but where anti-American sentiment is rife.

Police official Zulifqar Hameed said a judge ordered Davis be held another eight days. His next court appearance is set for Feb. 11.

Davis was arrested Jan. 27. Besides the two men who were shot dead, a bystander was also killed when he was struck by an American car rushing to the scene to help Davis.

Also Thursday, gunmen in southwest Pakistan shot dead the driver of a truck believed to be carrying supplies for NATO troops across the border in Afghanistan. The driver’s assistant was also wounded in the attack near the border town of Chaman, security official Abdul Sattar said.

Militants and ordinary criminals in Pakistan frequently attack trucks carrying supplies for Western troops in Afghanistan. The shaky security has led the U.S. to increasingly rely on other routes, including through Central Asian countries.