"The immigration department has just now blacklisted Najib and Rosmah from leaving the country," Mustafar Ali, director-general of the immigration department, told AFP.

Najib said in a tweet: "I have just been informed by the immigration department of Malaysia that my family and I are not allowed to go abroad. I respect the decision and I will remain in the country with my family."

Najib had earlier tweeted he was going to take a "short break". An angry crowd had descended on an airport near Kuala Lumpur where the couple had been expected to leave from, in a bid to stop them from departing.

After his defeat, speculation mounted the pair might flee the country as former strongman premier Mahathir Mohamad, who beat him in the elections, has pledged to probe a massive scandal in which Najib is implicated concerning the theft of billions of dollars of state funds.