The Burj Dubai tower under construction in the UAE has surpassed the 629 metre KVLY-TV mast in the US to become the world's tallest man-made structure, its builders have announced.

The KVLY-TV mast in Blanchard, North Dakota, had held the record for most of the 45 years since its construction, although it was topped between 1974 and 1991 by a radio mast in Poland that later fell down.

Developers Emaar have yet to reveal what the final height of Burj Dubai will be but it is expected to reach 900m when completed early next year.

At 160 storeys, Burj Dubai was already the world's tallest building exceeding the 508m of the Taipei 101 tower in Taiwan.

When completed, Burj Dubai will have used 330,000 cubic metres of concrete, 39,000 tonnes of steel reinforcement and 142,000 sq/m of glass, Emaar said.

A business website meanwhile reported plans by a Dubai-based competitor to build an even bigger building in the Gulf emirate.

State-owned Nakheel is planning a 1,200m-high tower that would comfortably surpass Burj Dubai, ArabianBusiness.com reported.

Nakheel, which is part of state-owned conglomerate Dubai World, told the website it was working with Woods Bagot but declined to discuss details of the project.

'We are finalising the design concept of a new project involving an iconic structure - Woods Bagot are a consultant on this project,' Nakheel said.

Saudi Arabia, which sits on a quarter of the world's proven oil reserves, is planning a 1,600m tower in the Red Sea city of Jeddah, according to the London-based Middle East Economic Digest.