Tribal chief Sheikh al-Ahmar Ali al-Aswad is holding the German family as bargaining counters for the release of five brothers who have been imprisoned by Yemeni authorities, according to a tribal spokesman identifying himself as Abu Khairalah
"The release of the five brothers is the only demand," he said, adding that "a pledge by sheikhs of other tribes or officials to solve the issue according to tribal traditions might suffice".
The five brothers, who belong to the Al-Abdullah Al-Daham tribe, were imprisoned "because of a tribal vendetta that they have nothing to do with," he added.
But a delegation of tribal chiefs and local councillors has been formed to negotiate a peaceful release of the hostages, an official told AFP.
"Authorities have not resorted to force to release the hostages, and will try to convince the kidnappers to release them peacefully in return for a promise to look into their demands," the official said, requesting anonymity.
Meanwhile, Abu Khairalah said the hostages were in good health, and that he himself last saw them on Wednesday afternoon "after they were taken hostage."
He said that the hostages were moved afterwards to another place within the tribe's territory.
Showered with presents
"I saw them yesterday (Wednesday) around 1:00 pm (1000 GMT) -- a man in his sixties, and his wife and three children... They are in good health and have been showered with presents" from their captors, he said by telephone.
Earlier reports had said the German family was abducted some four days ago from a restaurant on the road to the southern port city of Aden from the eastern region of Shabwa, 480 kilometres east of the capital Sanaa.
A foreign ministry spokesman in Berlin confirmed the disappearance of Juergen Chrobog -- who served as German ambassador to the US from 1995 to 2001 -- and his family.
"Former foreign ministry state secretary Juergen Chrobog and his family are missing in Yemen," the spokesman told AFP.
Mr Chrobog, 65, served as foreign ministry state secretary under former chancellor Gerhard Schroeder and was seen as a gifted crisis manager.
Ironically, he helped secure the release of 14 German tourists taken hostage in Mali in August 2003.
After the September 11, 2001 attacks in the United States, Mr Chrobog traveled to Pakistan to negotiate the release of aid workers for the organisation Shelter Now being held in Taliban prisons in Afghanistan.
Reports said Mr Chrobog and his family were guests of the Yemeni junior foreign minister, who is a former Yemeni ambassador to Germany.