The UN Working Group on Arbitrary Detention has ruled that former opposition leader Anwar Ibrahim's detention in prison is not necessary, and urged his immediate release.

It called the deprivations suffered by Anwar as arbitrary when taking into account all the circumstances of the case.

“The Working Group considers that the adequate remedy would be to release Anwar immediately, and ensure that his political rights that were removed based on his arbitrary detention be reinstated," it said.

The opinion of the UN group was read out by PKR’s Padang Serai MP N Surendran at a press conference in the Parliament lobby today.

Surendran said the order is binding on Malaysia and Putrajaya risks damaging its international reputation if the order is ignored.

Anwar's daughter, Lembah Pantai MP Nurul Izzah, was grateful for the UN body’s decision calling for her father's release.

"It ensures that the sharp decline in human rights under Prime Minister Najib Abdul Razak's administration will not go unnoticed," she said.

The Working Group is a body under the UN Human Rights Council, in which Malaysia had previously been a member.

It consists of experts from Australia, Benin, Mexico, South Korea, and Ukraine.

They held deliberated over Anwar's case for two months before reaching the decision which was given to the PKR de facto leader's lawyers in early October.

Nurul Izzah said the group is expected to make public its report this month.

Anwar was sentenced to five years in jail in February after the Federal Court upheld a Court of Appeal ruling holding him guilty in sodomising his former aide Saiful Bukhari.