US glam rocker Adam Lambert is "morally unfit" to perform and poses a threat to young people, PAS said today, vowing to protest his performance.

Lambert, who shot to fame in the American Idol contest, is openly gay and has created controversy with his performances, including at the American Music Awards where he simulated a sex act on stage and kissed a male keyboard player.

The authorities have given the green light to Lambert's show on Thursday in Kuala Lumpur, part of his Glam Nation tour, despite objections from the conservative Islamic party.

"Lambert is morally unfit. His gay lifestyle will harm our society. He is of bad, bad character and poses a danger to young Malaysians," said PAS youth chief Nasrudin Hassan.

NONE "We want the government to cancel the permit. The country is battling a serious problem of moral decay. We are experiencing rising social violence and crime," he told AFP .

Nasrudin said party members will protest outside the stadium where Lambert is due to perform, and will distribute leaflets discouraging people from attending the show.

"We will use a soft approach to protest against his performance. He has admitted he is gay.

"We feel his lifestyle will influence and destroy the young generation. We will not use violence to stop the concert," he said.

Homosexuality is a criminal offence in Malaysia, with penalties of up to 20 years imprisonment.

Lambert has agreed to demands from the authorities to tone down his performance here.

In Kuala Lumpur, meanwhile, about 20 members of several Muslim student groups held a brief protest gathering calling for the government to order that the concert be called off.

In their memorandum on the matter, Islamist student group Gamis demanded that the minister in charge of religious affairs Jamil Khir Baharom state his position on the issue, and accused the government of nonchalance.

"We question why this concert was approved despite there being a code of ethics when foreign artists perform (here). What is clear is that this artist (Lambert) is not qualified to perform here," said the groups.