The explosion happened in the Sayyida Zeinab quarter of Damascus, which features a Shiite shrine frequented by Iranians, according to Al-Jazeera and Al-Arabiya television networks.

Iran’s state television reporter in Damascus said the bus exploded while it was refuelling at a petrol station, about 500 metres (yards) from the shrine.

Al-Manar television, run by Lebanon’s Hezbollah Shiite militia, said the blast could have been caused by a gas bottle carried by the pilgrims in their luggage.

It said among those killed were the driver, his assistant and a mechanic.

Witnesses reported ambulances and fire engines racing to the scene, which was cordoned off by police.

Bankrolled by Dubai World, a government-owned conglomerate, he built a submarine workshop on the Persian Gulf, lived rent-free in a villa with a pool and tooled around town in a red Lamborghini. He had two Hummers. He vacationed with local plutocrats.

Jaubert said he heard whispers about Dubai’s darker side — the abuse of desperate laborers from impoverished Asian lands, the jailing of the occasional Westerner who crossed a sheik — but “I brushed it all off. I saw glamour. I saw marble columns, mirrors and money.”

More than one million people, the majority of them women and children, are smuggled across international borders to work in near slavery every year, the US state department says.

Its 2009 Trafficking in Persons Report lists more than 170 countries which it claims are not doing enough to tackle the problem.

Al Jazeera met “Svetlana”, a Ukrainian forced to work in the sex trade in Dubai and Abu Dhabi.

She recounted how she was offered a job as a waitress, but the woman who had originally promised to help her in Tashkent took away her passport and threatened to harm her family if she did not co-operate.