A hot air balloon accident that killed 19 tourists in Egypt was caused by the "grave" pilot error that caused a gas leakage, a police forensic report has found.

The interior ministry report blamed the manager of the hot air balloon port and the pilot for the February 26 accident that killed the Asian and European tourists.

The report, prepared by a ministerial forensic team, said "a grave error" led to a gas leakage that ignited the balloon in mid air, but did not elaborate.

The balloon was carrying 21 people at an altitude of 300 metres (1,000 feet) during a sunrise flight over the ancient temple city of Luxor when it caught fire.

Victims included nine Hong Kong tourists, and Japanese, British, French and Hungarian.

Two people survived by jumping out of the basket before the balloon hit the ground.

The pilot, who survived by leaping out before it went up in flames, was subsequently arrested.