Human Rights Watch is calling on Malaysia to repeal its anti-sodomy laws.

The global gay rights group has criticised the country’s government following its decision to appeal the acquittal of opposition leader Anwar Ibrahim on sodomy charges.

The charges against Mr Anwar were thrown out in January 2012, but Human Rights Watch (HRW) alleges that sodomy laws are once again being used to persecute the politician.

“Malaysian authorities are only adding insult to injury by appealing Anwar’s acquittal, compounding the injustice already inflicted on Anwar and his family,” said Phil Robertson, deputy Asia director of HRW. “The best way to ensure this kind of politically motivated persecution doesn’t happen again is for the government to abolish the hateful law on which it’s based.”

In 1998, Mr Anwar was imprisoned on charges of sodomy and corruption and sentenced to 15 years in jail, but this was overturned in 2004. However it took another four years before he could legally return to politics.

Mr Anwar was arrested again in 2008 after a male aide accused him of sexual assault, but the case was dismissed in January 2012 after new DNA evidence emerged.

Although the trial ended in acquittal, the case was marred by procedural problems that raised serious fair trial concerns. During the trial, the prosecution refused to share a number of critically important documents with the defence counsel including lists of witnesses to be called at court, surveillance tapes at the apartment where the alleged offence took place, and most crucially, access to DNA samples and original medical reports.

Government leaders regularly made public comments on the trial and the prosecution made obvious procedural breaches, such as leaking information from an on camera fact-finding visit by the court.

Should Mr Anwar lose the latest appeal, he faces a prison sentence of up to 20 years, and whipping. He would also have to relinquish his parliamentary seat and be barred from standing for election for five years if he is imprisoned for even 1 day or fined more than RM 2000 (£377).

Prosecutors originally charged Mr Anwar under article 377 of the penal code, a Victorian-era British colonial law that criminalises any activity that the authorities decide constitutes “carnal intercourse against the order of nature.”

Human Right Watch’s Phil Robertson added: “Anwar never should have been charged in the first place because consensual sexual relations between adults should never be criminalised.

“Malaysia should fulfil its obligations as a member of the Human Rights Council and bring its rights practices into compliance with international standards.”

A November 2011 report by the UN High Commissioner for Human Rights, presented to the UN Human Rights Council in March 2012, recommended that UN member states “repeal laws used to criminalise individuals on grounds of homosexuality for engaging in consensual same-sex sexual conduct.”

Malaysia is one of the 41 Commonwealth countries where homosexuality is outlawed.

Last year, the Malaysian Information Department banned television shows featuring gay characters.