"We have engaged tribal elders of the area for their release," Arif said.

The government workers were travelling from Peshawar, the capital of North West Frontier province, when they were seized near the town of Mir Ali.

Many foreign al-Qaeda fighters took refuge in North and South Waziristan after US-led forces forced the Taliban out of Afghanistan in 2001.

Last year the government reached a deal with the ethnic Pashtun tribes in the region reviving their traditional powers in an attempt to isolate foreign fighters.