Yemeni tribesmen have released a group of 24 local and foreign medical workers they had abducted from a Saudi-funded hospital in the country's north.

The doctors and nurses were released unharmed on Friday, after receiving assurances that two prsioners would be released in return.

The medics, most of whom were Yemenis but also included one Egyptian, two Indians and two Filipinos, had been abducted in the northern Saada region, just one day earlier.

The medics were travelling on a hospital bus at the time of their abduction, an unnamed government official was reported by the Reuters news agency as saying.

Sheik Hezam al-Amrani, whose tribe was involved in the abduction, said that the 24 abducted medical workers were freed after the kidnappers received assurances through mediators that their demands would be met.

Saada, where the medical workers were abducted, is where in 2004 tribesmen led by members of the al-Houthi family began an intermittent uprising against the government.

The tribesmen cited alleged economic and religious discrimination as the reason for their armed campaign.

Tribesmen often kidnap Western tourists in Yemen to press the government into providing better services and living conditions.

Most foreigners abducted in Yemen are released unharmed, but in 2000 a Norwegian was killed in crossfire and in 1998 four Westerners were killed during a botched attempt to free them.