A suicide bomber crashed a car packed with explosives into the tourists' convoy as they were ending a tour of a temple which dates back 3,000 years, to the time of the biblical Queen of Sheba.

Yemen has been trying to promote the temple as a major attraction and bring valuable tourist revenue in the impoverished country.

"This incident is a blow to the national economy and will affect tourism but should not affect investment," Saleh said.

Spanish aircraft

A Spanish aircraft was due to arrive in Yemen on Tuesday to pick up the remains of the three men and four women killed in the attack. Five wounded survivors will also be taken home on the aeroplane.

"Preliminary information indicates that the al-Qaeda organisation is behind the cowardly attack"

Interior ministry official
Security sources said the attack came after al-Qaeda released a statement demanding the release of some of its members jailed in Yemen and threatening to take unspecified action.

DNA tests were being carried out on the remains of the suicide bomber to try to ascertain his identity, Saleh said, adding that evidence so far indicated he was a non-Yemeni Arab.

"Preliminary information indicates that the al-Qaeda organisation is behind the cowardly attack," an interior ministry official told the state news agency on Monday.

Yemen has been fighting a domestic organisation linked to al-Qaeda which includes people on the US most-wanted list, including the men convicted of planning the USS Cole bombing.

USS Cole attack

Monday's attack was the deadliest against foreign nationals in the Gulf country since 17 American sailors were killed in the al-Qaeda attack on the US vessel off the port of Aden in October 2000.

Thirty-six Yemenis are currently on trial charged with planning and carrying out attacks for al-Qaeda but several of them are being tried in absentia after tunnelling out of a prison in the capital Sanaa in February last year.

Two suicide attacks on oil and gas installations in Yemen were foiled in 2006, days after al-Qaeda urged Muslims to target Western interests across the Gulf region. Al-Qaeda's wing in the country claimed responsibility and vowed to carry out further strikes.