The mystery caller who spoke to MH370 pilot Zaharie Ahmad Shah for 45 minutes a month before the doomed flight has been revealed as his cousin.

Zulhaimi Bin Wahidin, a former Malaysia Airlines engineer, denies he provided information to bring down the plane and also refuted talk his relative would have deliberately crashed the aircraft.

Mr Zulhaimi, who spoke with Zaharie at length on the phone on February 2, 2014, said he had been interviewed multiple times by Malaysian officials who held suspicions he had provided information to hijack the Boeing 777.

MH370 vanished during a flight from Kuala Lumpur to Beijing on March 8, 2014 with 239 passengers and crew on board.

“I was at police headquarters for three days,” told The Australian. “It spanned from morning to evening.

“I told them that Zaharie is a smart guy. He doesn’t need me to get all of the information.”

He said it was common knowledge at the airline they were related, with the pair sharing the same grandfather.

A report leaked two months after the flight went missing revealed police were suspicious of the call the pair had shared, as well as three attempts by Mr Zulhaimi to contact Zaharie after the plane was announced missing.

“That was not the first and last phone call,” he said of the lengthy chat.

“He had been calling me every week practically for the last 10 or 20 years.

“He’s a simulator instructor and the simulator is located near to my house.

“So each time when he wanted to go for simulator training, he would call me, ‘Are you in the house now? I want to visit you’.”

Mr Zulhaimi said he tried to make three calls to his cousin between 10.27am and 11.12am the day the plane went missing because he was in disbelief.

MH370 disappeared on March 8, 2014, along with with 239 passengers and crew.

The plane is believed to have crashed in the southern Indian Ocean after veering way off course and it disappearance remains one of the world's greatest aviation mysteries.

But Mr Zulhaimi denied his cousin was at fault, or that he deliberately brought down the plane.

“They’re trying to blame him for what happened and it’s very hard for me to swallow that because he’s not that kind of a person,” he said.

“He was a jovial person. He had a lot of money. He was enjoying his life.

“Why would he kill himself for no reason? He had a good family and a good life. Successful children.

“Of course (he is innocent).”

Mr Zulhaimi said Zaharie was like a brother, with the pair going to school together, working together, and spending time together outside of work.

Five years on, he said the family had “tried to forget about it”.

“We just accept the fact that he’s dead by now, I think,” he said.

“I spoke to his elder brother, his sister, we accepted it. It’s become normal now.”