KUALA LUMPUR (REUTERS) - Friends and family of the co-pilot who flew the missing Malaysia Airlines plane said the 27-year-old had wanted to become a pilot since his school days and worked hard to fulfill his dream.

They also described First Officer Fariq Abdul Hamid as a religious person.

"He is a good student. He worked very hard to get where he was. His parents are so proud of him," said a relative who had visited Mr Fariq's family home for prayers in the outskirts of the Malaysian capital Kuala Lumpur.

The relative, who asked not to be identified, confirmed that police had questioned Mr Fariq's family about his background this week.

The son of a high-ranking civil servant in Selangor state, Mr Fariq was often seen attending prayers at a mosque near his home, family and friends said.

"I haven't stopped praying to Allah in hope that my grandson and the other passengers are safe," his grandmother, Halimah Abdul Rahman, 84, told media in the northeastern state of Kelantan from where the family hails.

"He is a good person, respectful to elders and religious," she said.

Mr Fariq joined the national flag carrier in 2007 and had clocked a relatively few 2,700 hours of flying. He was helping to fly the Boeing 777 whose disappearance on Saturday has turned into one of the world's greatest aviation mysteries.

The focus of the probe could be turning to the flight crew or passengers with aviation experience after sources with knowledge of the Malaysian investigation told Reuters they increasingly suspect foul play.

Australian media earlier reported that Mr Fariq and a pilot invited two women to join them in the cockpit on a flight from Thailand to Malaysia in 2011, where he smoked and flirted with them.

Ms Jonti Roos, a South African living in Melbourne, confirmed to Reuters that the incident took place but said she did not feel that Mr Fariq behaved irresponsibly.

She said she assumed passengers were allowed to fly in the cockpit in 2011 and would not have done so if she had known it was against regulations.

"I thought that they were highly skilled and highly competent and since they were doing it that it was allowed," she said.

"I want to make it clear, at no point did I feel we were in danger or that they were acting irresponsibly."

Former and current Malaysia Airlines flight personnel said inviting passengers into the cockpit was rare, while smoking in the cockpit was frowned upon, although it did happen.

"It is a very male atmosphere in the cockpit. He was probably trying to fit in," said a former air stewardess with Malaysia Airlines who declined to be identified. "It can be a high-pressure job. It is not easy."

Malaysia Airlines said it was shocked by the allegations in the report, which was based on photos of the apparent cockpit meeting and an interview with Ms Roos.

Smoking has been banned on almost all commercial flights since the late 1990s. Cockpit doors have been reinforced since the Sep 11, 2001, attacks on New York and Washington and passengers have largely been barred from entering the cockpit during the flight since then.

The report angered some of Mr Fariq's friends who took to social media to rebut the report first aired by Australian Channel Nine's A Current Affair programme.

They said his character was very different to the one portrayed in the report.

"As a friend, I vehemently disagree (with) the allegations made by Ms Roos. The Fariq I know is soft spoken and quite shy," said a friend who goes by the twitter name @Herleena Pahlavy.

Mr Fariq's relative, referring to the report, said: "It is a very cruel thing to do at this time. We just want him to be safe."