The Burj Dubai or Dubai Tower has become the world's tallest building.

The developers say the project is already a year and a half ahead of completion and already stands at 512 metres.

If independently confirmed, it will take over as number one from the Taipei 101 in Taiwan, which has dominated the world's skyline at 508m since 2004.

The final height of the Burj, expected to be finished by the end of 2008, is a closely guarded secret, but the state-owned development company, has said that construction work will stop after the tower reaches 700m.