Abdul Ahad Karzai, a former diplomat, was gunned down by two assailants as he came out of a mosque after prayers, an official statement said. The gunmen, armed with automatic rifles, arrived on a motorcycle and drove off immediately after the shooting.

Two other worshipers, both Pakistanis, were also killed in the firing outside the mosque located at a marketplace in Quetta, capital of Pakistan's southwestern Baluchistan province bordering Afghanistan, the statement said.

Family sources said Karzai, who had been living in the United States, had arrived In Pakistan a few days ago.

Police said they had no immediate idea as to the motive for the killings.

Raids were conducted by the police in different parts of the city overnight in a bid to trace the killers, a police spokesman said.

Karzai was the fourth Afghani politician tobe killed in Quetta since last year. Those murdered before him included a former governor of Afghanistan's western Herat province, Nazar Mohammad.

Zahir Shah, who lives in Rome, recently aired a proposal to gather a cross-section of Afghani people to consider ways to restore peace and stability to Afghanistan.

The ex-king has drawn condemnation in the past from the Taliban Islamic militia, which rules around 80 percent of the country.