No-one has yet claimed responsibility for the attack

Seven Spanish tourists and at least two Yemenis died in the blast at the Queen of Sheba temple in Marib.

About seven others were injured in the attack which the Spanish foreign minister said he "totally condemned".

Yemen has faced continuing unrest in recent years, which the government often blames on al-Qaeda operatives.

An interior ministry official was quoted by the country's state news agency as saying that the attack appeared to have been carried out by al-Qaeda.

"Preliminary information indicates that the al-Qaeda organisation is behind the cowardly attack," the official told the Saba news agency.

ATTACKS IN YEMEN October 2000: Seventeen US sailors die in suicide attack on USS Cole in Yemeni port October 2002: A similar attack against French tanker the Limburg kills one Bulgarian and wounds 12 others March 2003: A Canadian is killed and another wounded after a Yemeni gunman opens fire at an oilfield east of Sanaa Sept 2006: Four bombers and a security guard die when Yemeni security forces foil suicide attacks against two oil refineries

Witnesses said a vehicle entered a gate at the site, known in Yemen by its Arabic name Balqis, before it ploughed into the convoy of tourist cars and exploded.

The victims were reported to belong to a group of around 14 Spanish tourists visiting the site, some 170km (110 miles) east of the capital, Sanaa.

Witnesses said the bomb went off at around 1800 (1500 GMT) on Monday as the visitors were finishing a tour of the temple, built 3,000 years ago at the time of the Queen of Sheba.

In recent years Yemen's government has been fighting Islamists with the help of US special forces based in Djibouti, on the Horn of Africa.