Malaysian Prime Minister Najib Razak said he had done nothing wrong in receiving hundreds of millions of dollars into his personal bank accounts, as his party opened its annual meeting on Tuesday amid tensions over a festering funding scandal.

Najib has so far weathered calls for him to quit over allegations of graft at state fund 1Malaysia Development Berhad (1MDB) and his receipt of 2.6 billion ringgit ($610.8 million) in what he says was a political donation.

But pressure is mounting on Najib as the saga causes a rift between top leaders in his United Malays National Organisation (UMNO), which has ruled the country for 58 years but looks increasingly at risk of losing the next election.