Malaysian former prime minister Mahathir Mohamad has announced he is leaving the country's ruling party amid a corruption scandal that threatens to engulf current PM Najib Razak.

Mohamad said he could no longer remain part of the United Malays National Organisation (UNMO), which has long dominated Malaysia's political landscape, because it was protecting Najib. Najib has been accused of funnelling $70 million from a state-owned fund into his personal accounts.

In comments reported by the New York Times, Mohamad said: "I want to leave UMNO because it is no longer UMNO. It is a party dedicated to protecting Najib. I can't be a member of such a party."

"I feel embarrassed that I am associated with a party that is seen as supporting corruption," he added. "It had caused me to feel ashamed."

The so-called 1MBD scandal, which has been going on since July 2015, has led to calls for the removal of Najib from his position, after it was discovered that the 1 Malaysia Development Bhd (1MBD) fund he set up in 2009 was $11bn (£7.9bn) in debt.

Furthermore, it was alleged by The Wall Street Journal that $70m (£50m) had been funnelled from 1MBD directly into Najib's accounts, an allegation he has denied, and that total bank deposits into his accounts topped $1bn.

His party have thus far stood by their prime minister, something Mohamad said meant he could no longer be a part of UNMO.

Mohamad has been a central figure in Malaysian politics for many years, serving as prime minister and as head of the party from 1981-2003, although he has previously left and re-joined the party on two other occasions.

He remains an influential figure, and his open lack of support for Najib has not helped the cause of the embattled prime minister.