The wife of a passenger travelling on the missing Malaysia Airlines flight has spoken of her struggle to cope as she continues to wait for news on the whereabouts of her husband.

Four days after the aircraft disappeared from the radar, Danica Weeks is still waiting for news on her husband Paul with investigators no closer to establishing what happened.

"I know I want to know but at the same time I don't want to know because the enormity of it at this stage is too much to process," she told Australia's Channel 7.

"How do you say your dad's lost?", she added as she described the difficulty in looking after the couple's two children, Lincoln and Jack, in Perth, Australia, while dealing with the ongoing situation.

The engineer was reportedly heading to Mongolia to start a new job when the flight bound for Beijing disappeared in what officials have described as an "unprecedented mystery".

Ms Weeks said she is comforted by the knowledge that Paul would be "trying everything in his power to get back and survive" if there is any hope of survival.

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Officials have extended the search area in efforts to locate the missing plane while Interpol has said it is unlikely the incident is linked to terrorism.

Despite her obvious resilience, the 38-year-old eventually broke down after a journalist commented on how proud her husband would be of her.

She said would continue looking after her children, and "Paul's legacy", to make him proud as efforts to find him and the other 238 people on board are stepped up.

Read: Search widens for missing Malaysian plane and its 239 passengers