The family of MH370 pilot Zaharie Ahmad Shah has lashed out at people who blame him for the disappearance of the Malaysia Airlines Boeing 777 with 239 people on board 12 months ago.

"Disgusting … no-one, be you politician, scientist, aviation expert, plane crash investigator, pilot, retired pilot, media or whoever, none of you have the right to blame Captain Zaharie Ahmad Shah for any wrongdoing," Sakinab Shah, the 53-year-old pilot's elder sister said in a statement to mark Sunday's anniversary.

Ms Sakinab's comments come as Malaysia is set to release a report on the investigation into the disappearance of MH370 on Sunday that could shed new light on one of the biggest mysteries in aviation history.

The findings of an investigation team comprising experts from seven countries have been shrouded in secrecy as the anniversary prompted renewed speculation and more wild theories about how one of the world's most sophisticated aircraft could disappear while flying over the South China Sea en-route from Kuala Lumpur to Beijing early  on March 8, 2014.

The report will detail the findings of extensive investigations into the plane, its flight path, crew and passengers and the data that led experts to conclude the plane crashed into the southern Indian Ocean west of Perth.

A key focus of the investigation has been whether someone deliberately switched off the plane's transponder and communications equipment as the plane was leaving Malaysian air traffic control and entering that of Vietnam.

Captain Zaharie and his co-pilot Fariq Abdul Hamid have been at the centre of a "rogue pilot theory" – one of the more plausible explanations for the disappearance, despite a lack of motive.

But Ms Sakinab accused the media of pouncing like "hungry starved wolves with their twisted and conniving interpretations" after Nik Huzlan, a retired Malaysia Airlines pilot who knew Captain Zaharie for 30 years, said last week he is convinced that someone in the cockpit caused the plane to cease communications and turn around from its scheduled flight path.

Mr Huzlan said there was nothing to suggest in Captain Zaharie's past he was capable of such a deed but added "your best friend can harbour the darkest secrets".

But speaking on behalf of her family Ms Sakinab said her brother, who was married with three children and one grandchild, was a  loving man "who stopped at nothing to render help when it was needed".

She said her family continue to pray and believe that "no matter how long the night, dawn will still break".

On the eve of the anniversary Malaysia's Transport Minister Liow Tiong Lai called for international aviation authorities to force improvements in air safety, including making aircraft tamper proof. Mr Liow said Malaysia has improved co-ordination between its military and civilian aviation authorities to avoid confusion and mistakes that plagued the initial search for MH370.

Malaysia Airlines has also started tracking its long-haul flights every 15 minutes or less as part of a trial with other countries, including Australia. Previously Malaysia Airlines tracked its fleet every 30 minutes.

Malaysia is required by the International Civil Aviation Organisation to release an interim report on the anniversary of the disappearance. The Malaysian-led investigation team, set up in April last year, included experts from Australia, the United States,  Britain, China, Singapore, Indonesia and Singapore. It also includes officials from Boeing and British satellite communications company Inmarsat.

An Australian-led search of 43 per cent of a designated high-priority area of the Indian Ocean has found only empty shipping containers and no trace of the plane.

"I think on the balance of probabilities at the moment, the chances of finding it are still good and we should be patient and persist with the search," said Angus Houston, Australia's former defence chief who is overseeing the Australian-led effort to find the plane.