Malaysia MH370: No trace yet after two-thirds of sub's scan

A submarine scanning the ocean floor for signs of a missing Malaysian airliner is two-thirds of the way through its search but has yet to find the plane, officials say.

The Bluefin-21 submarine was to embark on its ninth search mission on Monday.

Malaysia Airlines flight MH370 went missing in March as it flew from Kuala Lumpur to Beijing carrying 239 people.

On Monday another Malaysia Airlines flight was forced to land after one of its tyres burst on take-off.

Up to 10 military aircraft and 11 ships were to take part in Monday's search for MH370, Australia's Joint Agency Coordination Centre (JACC) said in a statement.

JACC said that the Bluefin submarine was searching a circular area with a 10km (six miles) radius where underwater signals were detected earlier this month.

The Bluefin-21, operated by the US Navy off the Australian vessel Ocean Shield, is an autonomous underwater vehicle (AUV) that can identify objects by creating a sonar map of the sea floor.

So far the submarine had scanned two-thirds of the area with "no contacts of interest", JACC said.

It is operating at a depth of more than 4,000m (13,000 feet).

Planes and ships will continue to scan the ocean for visible debris in an area spanning almost 50,000 sq km (20,000 sq miles), JACC said.

Authorities warned that weather conditions in the search area were deteriorating as tropical cyclone Jack approached.

In a separate incident, it has emerged that a Malaysia Airlines flight from Kuala Lumpur to Bangalore, India, was forced to turn back after one of its tyres burst.

The plane circled Kuala Lumpur for four hours to burn off fuel before landing.

The plane was carrying 159 passengers and seven crew members. There were no reported injuries.

The airline initially said the landing gear of the Boeing 737-800 had "malfunctioned upon take-off", but later said that a burst tyre was at fault.

It follows another incident in March when a Malaysia Airlines flight to Seoul was diverted to Hong Kong because of an electrical fault.

The incidents will increase scrutiny of Malaysia Airlines, which is facing heavy criticism by families of those on board flight MH370 for its handling of the disappearance.

Authorities still do not know why the plane flew so far off course and finding the plane's flight recorders is seen as key to understanding what happened.

Using satellite data, officials have concluded that MH370 ended its journey in seas west of the Australian city of Perth.