PUTRAJAYA (THE STAR/ASIA NEWS NETWORK) - Malaysia's Immigration Department has revoked the passports of sex blogger Alvin Tan and activist Ali Abd Jalil, both of whom have sought refuge in foreign countries.

Immigration Department director-general Datuk Mustafa Ibrahim said the move was necessary so as to serve as a warning to those who insult the courts, the rulers and Islam.

"We have also blacklisted their names from the system and we will notify them via official letters that will be sent to their Malaysian addresses," he told a press conference here, on Monday.

Mustafa, however, said that the revocation of Tan and Ali's passports did not mean that they had been stripped of their citizenships. He said the two could still return to Malaysia, but with different documents.

"They will have to apply for an emergency certificate in the respective countries in order to come back," he said.

Tan, a 26-year-old former National University of Singapore scholar, claimed trial last year with his ex-girlfriend Vivian Lee to three charges under the Film Censorship Act, Sedition Act and the Penal Code.

Tan and Lee - known as the Alvivi pair after shooting to fame with their now-defunct Sumptuous Erotica sex blog - still face two charges under the Film Censorship Act and Sedition Act for an insensitive "Ramadan greeting" that was posted on their blog last year. But he jumped bail earlier this year when he vanished during a trip to Singapore.

Tan on Sunday challenged Malaysia's government to revoke his passport, hours after the Home Minister Ahmad Zahid Hamidi said his ministry would do so as early as Monday.

"Just do it," wrote Tan in a caps-locked and profanity-laden Facebook post. He also called Zahid a "coward".

Tan claims he is in California and applying for asylum status in the United States.