Jakarta. A human rights group says next week's planned mass protest rally by hardline Muslim groups against inactive Jakarta Governor Basuki "Ahok" Tjahaja Purnama is a "trial by mob" and therefore unlawful and undemocratic.

The Jakarta-based Setara Institute has urged police to take firm action to prevent the rally, expected to take place in Central Jakarta on Dec. 2, from proceeding.

Police have warned demonstrators against occupying the main roads over concerns that it may disturb the public order.

"A demonstration must take place in a way that does not break the law. Rolling out prayer rugs on Jakarta's main streets is a form of protest that constitutes a violation of the law," Setara Institute chairman Hendardi said in a statement on Tuesday (22/11).

"Police must prepare measures to enforce the law against vigilante groups that break the law, pose threats and promote hatred," he added.

Next week's planned rally follows a similar demonstration in the capital earlier this month, which descended into violence. Muslim groups are protesting against Ahok over recent public comments regarding a Koranic verse.

Police eventually gave in to pressure by declaring the governor, a Christian of Chinese ethnicity, as a suspect in a blasphemy investigation. But Muslim groups planning next week's demonstration are now demanding his arrest, a move the police have so far resisted.

"The legal process cannot be put under any pressure whatsoever to undermine the independence of law enforcers. A trial by mob is undemocratic," Hendardi said.