Malaysia's Immigration Department says former scandal-ridden Prime Minister Najib Razak and his wife are barred from leaving the country, shortly after he announced plans for a short holiday.
A leaked flight manifesto shows Najib and his wife Rosmah Mansor were due to leave on a private jet on Saturday to Jakarta, fuelling rumours he was fleeing the country to escape possible prosecution over a massive corruption scandal involving the 1MDB state fund.
His coalition suffered a shocking electoral defeat this week that ended its 60 year-rule.
Later Saturday, Najib told a news conference that he was stepping down with immediate effect as president of the United Malays National Organisation as well as chairman of the National Front coalition. He said his deputy Ahmad Zahid Hamidi will take over as president of UMNO, a party that dominates the coalition.
The announcement followed strong calls from the party for the 64-year-old to step down.
"We accept the people's verdict with an open heart. Maybe this will be an opportunity for us to fix our weaknesses and shortcomings, although these are more a matter of perceptions than reality," he said. "God willing, UMNO will continue to live."
In his earlier statement on social media, Najib said he was committed to "facilitating a smooth transfer of power."
The Immigration Department, which had initially said there was no travel blacklist for Najib, issued a brief statement that Najib and Rosmah "have just been blacklisted from leaving the country."
Najib responded swiftly by saying he respected the department's ruling and will stay with his family in the country.
The National Front, which has ruled Malaysia since independent from Britain, obtained only 79 of the 222 parliamentary seats, losing power to Mahathir Mohamad's four-party alliance amid public anger over the 1MDB scandal and rising cost of living.
It was a remarkable comeback for Mahathir, who was premier for 22 years until his retirement in 2003.
Mahathir, who is now the world's oldest elected leader at 92, has said his government will not go on a witch-hunt over the 1MDB fiasco but that Najib will have to face the court if he's found to be responsible.
The fund was started by Najib when he took power in 2009, but it accumulated billions in debts and is being investigated in the US and several other countries.
US investigators said Najib's associates stole and looted $4.5 billion from the fund, of which some $700 million landed in Najib's bank account and some $30 million used to buy jewellery for his wife. Najib denies any wrongdoing.
