The five people displayed a banner calling on Mahathir to resign as he arrived at the International Islamic University Malaysia for a speaking engagement, the FreeAnwar Campaign said in a statement.

Campaign director Raja Petra Kamarudin said they were immediately detained and taken to a police station at Gombak in the capital's suburbs.

He told AFP he expected them to be released later Friday or Saturday. Police were not available for comment on whether they would face charges.

Raja Petra said the protest was part of a new strategy of attempting to stage a demonstration wherever the premier goes, in Malaysia or overseas.

"When we find out where he's going we will be there," he said.

"Whether it is Chicago, Washington or London, even if it is only one person standing with a Reformasi (Reform) flag, we will be there to greet him."

Raja Petra said Anwar supporters had distributed leaflets at a seminar for potential investors in New York on Monday, attended by International Trade Minister Rafidah Aziz.

Mahathir sacked Anwar on September 2, 1998. He was arrested 18 days later following mass anti-government rallies.

In April 1999 Anwar was jailed for six years for abuse of power and was last month imprisoned for nine years for sodomy. The sentences will run consecutively, meaning he will be in jail until 2014 unless granted the customary one-third remission.

Anwar says Mahathir orchestrated a conspiracy to frame him because he was seen as a political threat. The government denies any plot and says Anwar got a fair trial.

Anwar's supporters plan a nationwide programme of protest rallies next month. Recent demonstrations have attracted only small crowds in contrast to tens of thousands who took to the streets immediately after his arrest.