A prominent Malaysian opposition lawmaker, who has a reputation as a whistle blower, has been sentenced to 18 months in jail for releasing a classified document on a controversial state investment fund. A rights group slammed the jail sentence as a "dangerous chill" on free speech that could lead to a more repressive and unaccountable government.

Rafizi Ramli, vice president of the People's Justice Party, was found guilty by the court on Monday for violating the Official Secrets Act by possessing and disclosing part of a government audit report on the indebted 1MDB fund, founded by Prime Minister Najib Razak.

Rafizi, who often makes allegations on alleged government wrongdoing, said he will appeal. He risks being disqualified from running in the next general elections due in 2018.