“It is totally and absolutely the democratic thing to do,” he said of the ruling in his latest blog article. “All democracies in the world take away the passports of their citizens if they tell the foreign media anything bad about their leaders. Malaysians, under Najib’s democracy, must do the same.”

He said he would, when abroad, praise Najib “sky high” and speak well of the controversial RM2.6 billion deposit in his personal bank accounts.

“I will never fail to talk about Najib’s great contribution to Islam for which the Arabs gave him USD681 million. Also about the freedom of speech of Umno delegates to not talk about 1MDB and the 2.6 billion ringgit in the great leader’s account.”

Mahathir mocked administration officials who have said that a citizen’s acquisition of a passport is not a right but a privilege.

He said: “The passport is a privilege. It says so in the Malaysian Constitution. The constitution and the law also say that if you don’t praise Najib, the passport will be confiscated.

“​When I am abroad I will defend Najib and his democratic government. I give my word that I (with my tongue in cheek) will do so.

“Three cheers for 1MDB and money in the PM’s pocket.

“Now the country will become a big prison for those who talk against Najib to the foreign media when abroad.”