"We are sure that the aircraft took off from the wrong runway from the very beginning. It bumped into some steel items and heavy mechanical excavators and then exploded," said local prosecutor Song Kuo-yeh said.

Singapore Airlines had earlier dismissed speculation that the pilot became confused about the runways in bad weather, but now says that this was indeed the case.

"The aircraft was on the wrong runway, and we want to understand now how could this have happened," said Singapore Airlines spokesman Rick Clements.

Relatives of the 81 passengers who died have been arriving in Taipei to claim the bodies of the victims.

Flight SQ006 was bound for Los Angeles with 179 passengers and crew on board.

The black box flight recorder is still being examined, and Mr Song could offer no explanation for why the plane might have been on the wrong runway.

Parallel runways

The pilot and some survivors have said they felt the jet hit something just before the crash broke the plane into three pieces and set most of them on fire.

One theory is that the plane started its take-off run on the correct runway, but then swerved to avoid an obstacle and crashed onto the closed runway.

However, no skid marks have been found on the grass between the two runways.

A tropical storm, Typhoon Xangsane, could also have contributed to the crash.

Relatives arrive

This morning, more relatives arrived in Taipei on a SIngapore Airlines flight from Los Angeles.

Khan Mahmood from Atlanta, who lost his sister and his parents in the crash, criticised Singapore Airlines.

"Initially, we were disappointed. The first day it was a frustrating experience," he said.

There have been complaints that Singapore Airlines took too long to notify relatives about what had happened to the plane.

The relatives were taken to a memorial hall, where the bodies are waiting to be identified.

Coffins containing the remains of their loved ones are lined up in a makeshift morgue at the airport.