Incorrect weight data on an in-flight computer caused the tail of an Emirates plane to scrape the runway during take-off from an Australian airport, officials said yesterday.

The Dubai-bound Airbus A340 was forced to make an emergency landing an hour after taking off last month at Melbourne airport when the crew received a tail strike alarm.

Smoke began to enter the rear of the cabin as flight EK407 circled the airport for more than 30 minutes to dump fuel before landing safely and without any injuries. There were 257 passengers and 18 crew on board.

A preliminary investigation by Australia's air safety regulator found that the weight was entered incorrectly into the onboard computer.

"The result... was to produce a thrust setting and take-off reference speeds that were lower than those required for the aircraft's actual weight," the Australian Transport Safety Bureau said.

The plane's tail was seriously damaged as the captain manually increased thruster pressure, scraping the rear fuselage along the tarmac and the grass verge beyond the runway.