Muhyiddin Yassin has lamented that Prime Minister Najib Abdul Razak did not heed his call to sack the 1Malaysia Development Bhd's (1MDB) board of directors.

The deputy prime minister also wanted the ailing firm's top management to be probed by the police.

"I told the prime minister, sack all those guys, the board (of directors) of 1MDB.

"They should be sacked since because of them, the prime minister has to shoulder the burden. Yet, they have not been sacked," he said in a video uploaded on YouTube by former New Straits Times editor Firdaus Abdullah.

It is believed the recording is of Muhyiddin's speech at an event in Janda Baik last Saturday. It is unclear if this was a closed-door function.

Also seen in the 7-minute video clip were Home Minister Ahmad Zahid Hamidi and Deputy Finance Minister Ahmad Maslan who were sitting in the front row, as well as other top Umno leaders.

Muhyiddin also said the 1MDB chief executive officer should also be sacked and be investigated by the police.

"If the company is mine and when I wake up in the morning and read reports that the CEO had borrowed up to RM10 billion.

"And I have to pay between RM100 million and RM200 million in interest. I never thought that any company in the world would have to shoulder such a burden.

"So what do you do? You not only sack the CEO, you call the police to investigate them," he said.

Muhyiddin said if action is taken, the rakyat would see that the government is serious.

"If not, this will be a burden and will bring our downfall.  We have to take action, we cannot give them more time," he said.

No 'Milan plot '

The Umno deputy president again denied that a conspiracy was hatched in Milan, Italy, to topple Najib.

"It's all lies and slander. Don't believe easily what's on social media," he said.

Former law minister Zaid Ibrahim had claimed that Muhyiddin, ministers Nazri Abdul Aziz and Mustapa Mohamed as well as former finance minister Daim Zainuddin were among the conspirators who met in the Italian city.

Najib has come under intense fire over the problems plaguing 1MDB, with former premier calling on him to resign.

The prime minister, however, said the RM42 billion which his detractors claimed had "disappeared" did not just vanish.

Najib said auditing firms would not keep quiet even if RM1 million is lost. 1MDB is audited by auditing firm Deloitte.