Sana'a, Yemen  - Yemeni tribesmen have released a South African tourist and her two sons unharmed, a day after they kidnapped them in the southern province of Abyan to press for the release of a jailed fellow clansman, police officials said late Saturday.

The woman, the boys, ages 10 and 13, as well as a Yemeni driver were kidnapped on Friday as they drove on a highway from the south- eastern province of Hadhramout to the port city of Aden.

Armed tribesmen from the al-Maraqisha tribe stopped the family's vehicle near al-Khubar, 170 kilometres east of Aden.

The hostages' release was the fruit of "intensive engagement of police officials and tribal elders," in talks with the abductors, a police official told Deutsche Presse-Agentur dpa.

Tribal sources said that authorities had released the kidnappers' relative, whom they demanded to be freed from police custody in exchange for setting the hostages free. The prisoner was a police officer jailed for misconduct, the sources said.

The woman was among a group of South African tourists visiting Hadramout, officials have said.

The abduction occurred nearly two weeks after armed tribesmen released three Germans following a five-day kidnap ordeal. The kidnappers intended to press for the release of two relatives jailed in Sana'a over involvement in a previous kidnapping.

The hostages were released unharmed five days later.

Disgruntled tribesmen from impoverished areas of Yemen often take hostages to use as bargaining chips to press the government for aid, jobs or the release of detained fellow clansmen.

More than 200 foreigners have been kidnapped in Yemen since 1991. Almost all were released unharmed after mediation involving tribal leaders.

In September, armed tribesmen held two Colombian engineers hostage for three days in southern Yemen and demanded the release of a fellow clansman detained by police in connection with criminal offences. (dpa)