The head of the civil aviation authority in the United Arab Emirates today said investigators do not believe an explosion caused the crash of a UPS cargo jet in Dubai earlier this year.
But Saif al-Suwaidi added officials were taking a claim by Yemen's al-Qa'ida group that it brought down the plane seriously.
The director-general of the General Civil Aviation Authority said that while terrorism was not believed to be behind the crash, authorities are looking at all possible causes.
Asked if that included the possibility of a bomb that failed to detonate properly or another device sent to deliberately cause damage, al-Suwaidi said: "Everything is possible. We are revisiting everything."
He reiterated that there was no evidence of an onboard explosion in the September 3 crash, which killed the two pilots.
"A terror act is an unlikely cause. But it doesn't mean we eliminate it," he said. "The investigation is ongoing. Of course we are investigating all possibilities."
Yemen's al-Qa'ida in the Arabian Peninsula yesterday claimed responsibility for the crash of the UPS cargo plane and last week's international mail bomb plot.
In the September crash, a fire onboard the three-year-old Boeing 747-400 cargo plane prompted the pilots to turn back to Dubai shortly after take-off as the cockpit filled with smoke.
The cause of the fire is unknown. The plane crashed into a military base after attempting to make an emergency landing.
Crash investigators have found no evidence of an explosion on board, saying there was no recorded change in pressure or other information on data recorders to indicate a blast. An official familiar with the investigation in the US has also said there is no sign the crash was caused by a bomb.
The probe has been focused on determining whether the fire was caused by a technical malfunction or flammable cargo such as lithium batteries that power electronic gadgets such as cameras, mobile phones and laptop computers.
One of two packages in last week's mail bomb plot was discovered by UAE authorities in Dubai. The other was found at East Midlands airport in the UK.