The 124th-storey viewing platform at Dubai’s $1.5-billion Burj Khalifa has unexpectedly closed to the public, leaving hordes of tourists hanging.

Building company Emaar Properties said that electrical problems were partly to blame for the closure of the viewing platform at the world’s tallest building for repairs. The platform is closed indefinitely and it is unknown whether the faults extend to the rest of the building.

"Technical issues with the power supply are being worked on by the main and subcontractors and the public will be informed upon completion," the builder said in a statement.

The platform opened to the public following the dramatic naming ceremony of Burj Khalifa on 4 January, which was attended by 400,000 people.

The raised area is mostly enclosed but incorporates an outdoor terrace with guard rails. Visitors are charged $32 (100 AED) if they book in advance or $126 (400 AED) on the day.

The ascent to the 124th floor is by a double-deck elevator, each deck carrying up to 14 people and travelling at 10 metres per second.

Standing at 828 metres high, with 160 floors and more than 500,000sqm of office and residential space, the tower is clad in 28,000 glass panels.