Malaysia’s opposition leader Mahathir Mohamad is under investigation after allegedly breaching a new anti-fake news law by saying a domestic flight he took in April was sabotaged.

Critics of Prime Minister Najib Razak have suggested the laws criminalising the dissemination of “fake news” are an attempt to curb free speech in the run-up to the country's May 9 election next week.

A report by Malaysia's Civil Aviation Authority found no indication of sabotage, simply a “routine technical fault” with the aircraft’s wheels.