Malaysian authorities have barred a key former official from the troubled state wealth fund 1MDB and several opposition figures from leaving the country, in a move described as quelling public scepticism and clamping down on dissent.

The latest twist in the scandal surrounding the state-owned company closely linked to Prime Minister Najib Razak added to the mounting pressure on the Malaysian leader.

Nik Faisal Ariff Kamil, a former chief investment officer of 1Malaysia Development Bhd (1MDB), was the first key official from the fund to be placed on the travel blacklist since an investigation was launched into allegations that money had been siphoned off from the now heavily indebted fund.

… The move to impose restrictions on the former 1MDB official and critics was an attempt to quell scepticism about the ongoing investigation as well as suppress his critics, said Oh Ei Sun, a senior fellow with the S. Rajaratnam School of International Studies, Nanyang Technological University.

Oh said Najib was likely to ride out his biggest challenge of his career. “But as for how long he can survive, I really can’t tell,” he said. A source with close ties to Umno said many within the party now considered Najib as a “poison pill”. “They think it’s time for him to leave,” said the source.