Sleman, Yogyakarta – Outspoken Indonesian government critic George Junus Aditjondro is facing up to four years in jail for allegedly insulting the Yogyakarta royal family.

Snr. Comr. Kris Erlangga, head of criminal investigations at Yogyakarta Police, said on Thursday that George – an outspoken critic of former dictator Suharto and incumbent President Susilo Bambang Yudhoyono – had "found strong evidence that he had committed libel."

The charges relate to an attempt by George to make a pun about the Yogyakarta Palace, comparing it to a "watched monkey."

"The Yogyakarta Keraton [Palace] should not be equated with the UK kingdom," he said. "The Yogyakarta Keraton is only a keraton, or kera ditonton [Watched Monkey]," George said during a political discussion at Gadjah Mada University on Nov. 30.

Following the comments, dozens of people, accusing George of humiliating the royal Yogyakarta family and the people of the special province, raided his home in an attempt to expel him from the city.

Kris said George had been charged under Article 156 of the Dutch colonial-era Criminal Code, which carries a maximum penalty of four years imprisonment.

The article states that "a person who publicly gives expression to feelings of hostility, hatred or contempt against one or more groups of the population of Indonesia, shall be punished by a maximum of four years imprisonment or a maximum fine of Rp 300 ($0.033)."

The article defines the group as "part of the population of Indonesia that distinguishes itself from one or more other parts of the population by race, country of origin, religion, origin, descent, nationality or constitutional condition."

It is not immediately clear how this relates to the ruling royal family headed by Sri Sultan Hamengkubowono X, a Golkar politician who is automatically appointed governor of the special province.

George has not been taken into custody but is banned from leaving the country.