KUALA LUMPUR, Malaysia --

Malaysia Airlines said Tuesday that it was inspecting its fleet of Boeing 747-400 planes following a midair crisis in which a Qantas jet was forced to make an emergency landing with a hole in its fuselage.

The investigation into what caused the hole in the 747-400 last Friday continues to narrow on a missing oxygen tank that appears to have burst while the plane was flying at 29,000 feet (8,800 meters) over the South China Sea.

In a reply to queries from The Associated Press, Malaysia Airlines said it was carrying out initial checks on the support bracket of the oxygen cylinder on four of its 13 Boeing 747 aircraft and will conduct further inspection pending the findings of Qantas investigations.

"The failure of the bracket can cause a leak in the oxygen system and can become a fire hazard. It will deplete the supply of oxygen to the pilots or the passengers," said Mohamad Roslan Ismail, senior general manager for engineering and maintenance at the flagship carrier.

"We aim to complete the initial checks by the end of the week. We will continue to work with Qantas and Boeing, and will call out any (other) inspections as necessary," he said.

The Qantas 747-400 jet, carrying 345 passengers from London to Melbourne, Australia, was forced to make an emergency landing in the Philippines with a car-sized hole in its fuselage. No one was hurt.

Qantas chief Geoff Dixon said Monday that investigators had not determined what caused the hole, but his comments suggested the airline believed it was a mechanical fault - not human error.

Sydney-based Qantas was ordered to urgently inspect every oxygen bottle aboard its fleet of 747-400s following the scare.

Mohamad Roslan said inspection of the four Malaysia Airlines' planes was also in compliance with an April airworthiness directive from the U.S. Federal Aviation Administration.