LONDON - The wife of Captain Zaharie Ahmed Shah, the pilot of the missing Malaysia Airlines flight MH370, will be questioned amid growing suspicions he may have hijacked the plane, a British tabloid reported.

Madam Faizah Khan, mother of three, will be interrogated in an investigation supported by the FBI as the search for the plane enters its third week, The Mirror said on Monday.

American intelligence agents are said to be steering Malaysian officials towards examining the backgrounds of Captain Zaherie, 53, and his co-pilot Fariq Abdul Hamid, 27.

However a source close to the probe has revealed that vetting on Mr Fariq is almost complete - and has so far thrown up nothing untoward.

It means Mr Zaharie has now become the primary focus.

"There seems to be nothing in the life of Fariq Hamid to suggest a motive for hijacking. The personal life of Zaharie Shah, however, is far more complex and is in the process of being unravelled," The Mirror quoted the source as saying.

It appears Mr Zaharie's marriage had deteriorated to the point where he was no longer in a relationship with Madam Faizah, despite them still living together with their children, the British paper said.

Police are also examining reports that he received a two-minute phone call shortly before take-off on March 8 from a mystery woman using a mobile number obtained using a false identity.