Security is tighter than ever around Egypt's main tourist sites, one day after a bomb in Cairo's old bazaar killed two foreigners and raised the spectre of a fresh wave of attacks.

Thursday's blast, apparently caused by a booby-trapped motorcycle, was the first attack against foreigners in the capital in more than seven years and came amid unprecedented upheaval on Egypt's political scene.

Egyptian Tourism Minister Ahmad al-Maghrabi told reporters that a Frenchwoman and a US national had been killed in the blast, while the third victim had not yet been identified.

He said three Americans, two French and four Egyptians were being treated at the hospital. One of the French nationals was in serious condition while the other wounded were stable, he added.

No claim

There was no immediate claim of responsibility for the blast, but the authorities swiftly launched an investigation and tightened security around the country's main tourist attractions.

The US authorities warned their citizens to avoid tourist hubs in the capital pending further information on the nature of the explosion.

"While there is no independent information to suggest that this alleged attack was a part of a larger effort, all residents of and visitors to Egypt should be especially vigilant and avoid areas of Cairo where large numbers of tourists congregate," a US embassy statement said.

The Egyptian authorities attempted to play down the blast. "According to preliminary information, it was an individual operation, its perpetrator having used a home-made device consisting of powder and nails," said government spokesman Majdi Radi.

The blast struck one of the main alleyways to the famed Khan al-Khalili bazaar, which is in the heart of ancient Islamic Cairo and is popular with souvenir-hunting tourists.

The explosion plunged the district into darkness and the usually bustling streets of the famed bazaar were soon deserted, as tourists fled the area and shop owners hastily shut down their stalls.

In October, 34 people, including several Israeli tourists, were killed and more than 10 wounded in triple bomb attacks on the Hilton hotel Taba and two nearby resorts in the Sinai peninsula.

The Sinai bombings were the first such attacks against foreigners in Egypt since a wave of deadly bombings in the mid-nineties.

The fresh unrest in the capital comes amid moves by the opposition to Egyptian President Husni Mubarak's rule over the country and growing calls for lifting the 24-year-old state of emergency.

Mufti Ali Jumaa, Egypt's highest religious authority, condemned the attack and said in a statement that "it could only serve the purpose of those who are jealous of the country's stability".

PHOTO CAPTION

An Egyptian interior ministry vehicle at the site of a bomb blast in Cairo. (AFP)