Gunmen kidnapped a foreign doctor working with the International Committee of the Red Cross (ICRC) in the southwestern Pakistan city of Quetta Thursday, police officials said.

No one immediately claimed responsibility, but criminal gangs have often targeted foreign aid workers in the hope of securing large ransoms for their release.

The doctor was travelling to the Red Cross office when he was stopped by gunmen who forced him into their vehicle and drove away, police sources said.

An ICRC official confirmed that one of their employees, a foreign national, was kidnapped in Quetta, capital of southwestern Baluchistan province.

We are checking all routes out of the districts, but we have not been able to trace that vehicle. We are trying to ensure that the vehicle does not leave Quetta, Nazeer Kurd, a senior city police official, told reporters.

Baluchistan is Pakistan's biggest but poorest province, where Baluch separatist militants are fighting a protracted insurgency for more autonomy and control over the area's natural resources.

Pro-Taliban militants are also active in the province, which shares borders with Afghanistan and Iran.

Four health workers, including two doctors, were kidnapped by militants last week from the Pishin area of Baluchistan, near Quetta. They were freed after a shootout between police and their kidnappers.

The Pakistani Taliban said Thursday they had killed 15 soldiers kidnapped last month in revenge for military operations against them.

Officials confirmed that 15 bodies, with signs of torture and gunshot wounds, had been found in the Thal area of the northwestern Hangu district, near the unruly northwestern tribal areas along the porous border with Afghanistan.

(Reporting by Gul Yusufzai in QUETTA; Writing by Qasim Nauman; Editing by Nick Macfie)