MOSES ONCE allegedly parted the Red Sea to allow the Israelites to return home from exile in Egypt. But, as far as is known, no-one has walked across the 1400-mile long sea which divides Africa from Arabia and Asia since the man who gave us the Ten Commandments is said to have done the the trick some 3500 years ago.

But now Osama bin Laden's brother, Tarek, plans to build a 21st-century bridge of Biblical proportions across the southeastern end of the Red Sea between the Arabian country of Yemen and the African state of Djibouti.

The epic project - funded by Saudi Arabia and the United Arab Emirates - is being designed by a Danish engineering company, and a San Francisco firm has been hired to manage the building of the 18-mile-long bridge.

The bridge will take 12 years to construct with 100,000 workers at a minimum cost of $22 billion (about £11bn), probably rising to more than $70bn (about £35bn). New cities will be built at either end of the bridge, with the site at the Yemeni end - currently a sparsely inhabited area with only a few fishing villages - destined eventually to look like Hong Kong or Dubai.

Tarek, an older brother of Osama, the founder of al-Qaeda, is one of at least 54 children born by 22 wives to Mohamed bin Laden, a poor, uneducated Yemeni who emigrated before the first world war to Saudi Arabia. He went on to create a mighty construction business under the patronage of the first Saudi monarch, Abdul Aziz Ibn Saud.

Mohamed achieved such success that he and his offspring became known as the wealthiest non-royal family in the kingdom. The Bin Laden Construction company amassed assets worth billions of dollars, making its first profits from exclusive rights to all mosque and other religious building construction in Saudi Arabia. Until 1967, Mohamed bin Laden held exclusive responsibility for restorations at the Al-Aqsa Mosque in Jerusalem.

Tarek, 61, who has been described by business colleagues as "very intelligent, with a lot of charisma", now heads the Bin Laden Group. The headquarters remain in Saudi Arabia and it has the management contract for Mecca's holy sites. The group has more than 40,000 employees in Egypt alone.

In interviews Tarek has been reticent about his half-brother Osama, Mohamed's 17th child and the only son of his tenth wife, saying only that he has had no contact with him, that he does not know his whereabouts and that the family publicly disowned him in 1993.

But he is not reticent about his bridge - which will be the world's longest suspension bridge - to be built across the Bab el-Mandeb, or Gate of Tears, the narrowest point of the Red Sea before it opens out into the Indian Ocean.

He has given interviews enthusiastically describing his plans to build two mega-cities at either end of the bridge and then move further into Africa, with major projects already planned for Morocco and Mauritania. "These projects will give stability and fight poverty," he said. The Yemeni city has been christened Medinet al Noor, the City of Light.

The Bin Laden Group is about to launch an international roadshow to promote the Africa-Asia bridge and attract industries to its two landfalls, with Singapore and the United States the first destinations. "It is the project of the 21st century," said Tarek. "We hope that US, European and South African firms will invest and participate. Otherwise the others, such as China and India, will take most of it."

Yemen, which Tarek bin Laden regards as his native land, is the poorest country in the Arab world. But Tarek believes the bridge - with its six-lane motorway and four-track railway - and the $100bn city and free trade zone at the Yemeni end will transform the region's economy.

Both Djibouti - a sleepy, sweltering ministate with 83% unemployment and without a single traffic light - and Yemen have approved the project. Yemen has given Tarek bin Laden 500 square miles of territory, gratis, to build the City of Light, marked only at the moment by six cement plants erected by the Bin Laden Group.

If all goes according to plan, construction of the bridge will begin next year. It will comprise a two-mile conventional girder bridge from the Yemen coast to the offshore island of Perim. A two mile highway-railway across the island will then lead to a giant 14-mile suspension bridge jumping across the Bab el-Mandeb to Djibouti.

To allow oil tankers and other large vessels to pass underneath, two of the suspension bridge's spans will each be two miles long, suspended between 2300-feet-high concrete pylons, anchored to the sea bed 1300 feet below the surface of the water and then towering 1000 feet skywards.

Currently the longest suspension bridge in the world is the 2.5-mile Akashi-Kaikyo Bridge in Japan, which has a centre span of about 1.3 miles.