Mark Thatcher, son of British Prime Minister Margaret Thatcher, and the rest of his driving team were found and rescued today in the Sahara Desert, where they had been missing for six days from a transcontinental automobile rally.

An Algerian Air Force plane participating in an international search spotted Thatcher, his French codriver, Charlotte Verney, and mechanic Jean Garnier with their white Peugeot 504 in a remote area of Algeria near the border with Mali. A rescue team took them to the town of Tessalet in Mali, from where they later will be flown to Tamanrasset in southern Algeria, where Thatcher's father, Denis, is waiting.

Denis Thatcher telephoned his wife at 10 Downing Street here tonight to confirm his son's rescue. The prime minister said later, "I'm very relieved and thankful."

She said, "It has been an ordeal for all of us and not least for Charlotte Verney's elderly mother in France," with whom the prime minister has been in constant touch by telephone during the search. Both she and Denis Thatcher praised the Algerian government for their role in the rescue.

Mark Thatcher and his teammates were among many rally participants who had to be rescued from the desert during the most dangerous part of the route, which passes through France, Algeria, Mali and Senegal.

The desert track through the Sahara is unpaved and largely unmarked, running hundreds of miles west of the main, paved trans-Sahara Highway.

Three Italian journalists covering the event died last year, and a Dutch motorcyclist, a French journalist and a Malian youth have been killed in this year's rally.