A United Nations working group said yesterday that the imprisonment of former Malaysia opposition leader Anwar Ibrahim was "arbitrary" and called for his immediate release, according to a copy of the opinion made public by his family yesterday.

The opinion, made by the UN Working Group on Arbitrary Detention (WGAD) under the UN Human Rights Council, was adopted in September after a hearing which lasted over two months.

The group considered that Anwar had not been given a fair trial and that his detention was politically motivated.

"The Working Group considers that the adequate remedy would be to release Mr Ibrahim immediately, and ensure that his political rights that were removed based on his arbitrary detention be reinstated," the opinion stated.

Anwar is serving his eighth month of a five-year prison term after Malaysia's highest Federal Court in February upheld a Court of Appeal ruling that he had sodomised a former aide in 2008.

The WGAD opinion was announced at the Parliament lobby by Anwar's daughter, MP Nurul Izzah Anwar, flanked by other opposition allies.

She demanded proper medical services for her father in jail.

"Its (the opinion's) strong stance in solidarity with my father sends a clear and unequivocal message to Prime Minister Najib Razak, and ensures that the sharp decline in human rights under his administration will not go unnoticed," Ms Nurul Izzah said.

Responding to the WGAD report, Minister in the Prime Minister's Department Nancy Shukri, the de facto law minister, said the opinion seemed to question the integrity of Malaysia's judicial system.

"Who are they to say that? It is our law, it is our judiciary," Ms Nancy told The Straits Times.

In Parliament, Deputy Home Minister Nur Jazlan Mohamed said in the 38 weeks Anwar has been in prison, he has undergone treatment 33 times at the nearby Sungai Buloh Hospital. He has also attended 10 physiotherapy sessions for his shoulder problem.

Anwar has met his family 15 times, his lawyers 65 times, and performed Friday prayers 35 times - way above rights given to other prisoners, Datuk Nur Jazlan said.