Kuala Lumpur - A Malaysian court on Friday ordered the release of a popular anti-government blogger, ruling that his detention under a draconian security law was unlawful.

Raja Petra Raja Kamarudin was arrested on September 12 under the Internal Security Act (ISA) after the government said his articles incited hatred and racial discord as well as insulted Islam, the official religion.

The editor of the popular Malaysia Today website had denied the allegations and appealed against his detention, which could have been indefinite under the ISA's provisions.

Malaysia's High Court ruled that Raja Petra would be brought to court later Friday and immediately released from the detention centre in the northern Perak state.

Judge Syed Ahmad Helmy Syed Ahmad said that the home minister had acted outside his powers in having Raja Petra arrested, and ruled that his detention was unlawful.

The ISA is a law formulated during Britain's previous colonial rule to fight a communist insurgency. It allows the government to detain anyone for an initial two-year period without being charged and to extend the detention indefinitely.

Raja Petra, 58, is also on trial on separate charges of sedition, after he allegedly implicated deputy prime minister Najib Razak in the murder of a Mongolian woman in 2006. Raja Petra denies the charges.

Following the ruling, Raja Petra's wife Marina Lee Abdullah said she was very happy with his impending release.

"I am glad that everything turned out well. It is a fantastic breakthrough," she was quoted as saying by the Star online news portal.

Raja Petra's release was hailed by opposition leaders and fellow bloggers who said the ruling was a sign of growing judicial independence in the country.

"The court decision sustains hope that basic judicial decency, independence and integrity have not been completely destroyed," said Lim Kit Siang, a senior leader of the opposition Democratic Action Party.

Paul Sebastian, a fellow blogger, said Raja Petra's release was a victory for all who defended the freedom of speech and freedom of the internet.

"If what he says are lies, people are intelligent enough not to believe it.

"If what he says are the truth, then all the more there must be an avenue where the people have a chance to know," he said.

Raja Petra has in the past come under fire from the government for his often sensational articles, alleging wrong-doings by top leaders.