Dubai-owned airline Emirates said it would build one of the world's tallest hotels to cater for growing numbers of tourists to the Gulf Arab emirate.

The Dubai Tower will be the tallest building in the world when finished.It would dwarf the 553m CN Tower in Toronto and planned high-rises in Shanghai and New York.

Some 4000 worders and 100 cranes have gatered to build the hotel, residential and shopping complex of at least 700m which will include over 1000 luxury apartments.

The exact height is being kept a secret,partly for fera of rival bids to be the tallest free-standing building,and because by 2008 it might be technologically possible to go even higher.

Dubai-based architects say they expect Dubai Tower to hit at least 800m.The tower alone would cost at least $1 billion to construct, excluding the complex malls,lakes and smaller tower blocs.

"The design has pushed the limits of what technology can achieve, no one has gone that high before.You have to invent new elevators that can sustain such heights," Naaman Atallah,sales manager for its owner Fmaar told journalists on a tour of the site.

Designed by a US-based consultancy,the tower employs the geometric patterns of Islamic architecture around a base in the form of a sixpetalled desert flower.

The plans show an ambitious single structure comprising conjoined tube-shaped towers with the kind of space-age look seen in the New Age album covers of 70s progressive rock bands.

Dubai---part of the oil-rich United Arab Emirates received more than 5.4 million visitors in 2004,up nine percent from 2003,and that the number was expected to grow three times by the end of the decade.