AFP - Three members of a German family, among them a UN expert, have been kidnapped in Yemen and are being held in a mountainous area of the impoverished Arab country, a security official said on Monday.
  
The three were seized on Sunday in the Bayda area southeast of Sanaa and taken to Bani Dhabian, which lies 60 kilometres (40 miles) east of the capital but is difficult to access, the official said on condition of anonymity.
  
A tribal source told AFP that the kidnappers were tribesmen -- who have frequently used foreign hostages as bargaining chips with the government -- but that he did not know their demands.
  
A Western diplomat said the hostages were a German couple and their daughter, who works in Yemen.
  
"The mother and father were on a visit in Yemen, and they were kidnapped with their daughter as they were sightseeing in the province of Bayda," the diplomat said on condition of anonymity.
  
In Berlin, German foreign ministry spokesman Jens Ploetner said the three had been missing since Sunday from the outskirts of Sanaa and "we assume they have been kidnapped."
  
Yemen's powerful tribes have repeatedly abducted Westerners in recent years to put pressure on the government in Sanaa to respond to their demands. More than 200 foreigners have been abducted over the past 15 years.
  
All have been freed unharmed except for three Britons and an Australian seized by Islamist militants in December 1998. They were killed when security forces stormed the kidnappers' hideout.
  
Yemen, the ancestral homeland of Al-Qaeda chief Osama bin Laden where tribal traditions prevail, is one of the poorest countries on the planet and awash with weapons.
  
The southern Arabian peninsula country has seen several attacks by Al-Qaeda, including the October 2000 suicide bombing of the destroyer USS Cole that killed 17 American sailors.
  
In September this year, five Germans were part of a group of 19 European and Egyptian hostages seized by bandits while on safari in a lawless area of Egypt's southwestern desert on the Sudanese and Libyan borders and later freed.
  
In December 2005, armed Yemeni tribesmen captured a former German ambassador and foreign ministry number two, his wife and three children and held them for about five days.