A South Sumatra court sentenced two environmental activists to seven months in prison for provoking a riot against a sugar plantation, despite a public outcry against the criminalization.

Indonesian news portal Detik.com reported that Anwar Sadar, the director of the South Sumatra chapter of the Indonesian Forum for the Environment (Walhi), and Dedek Chaniago, the president of Indonesian Green Students (PHI), were found guilty of inflicting chaos by provoking a riot and sentenced them each to seven months in jail.

"From the evidence and the witnesses' testimony, we concluded that the suspect is convincingly guilty of article 160 in the criminal code," Judge Arnelia told the Palembang district court on Thursday.

Anwar, along with several farmers from the village of Betung in Ogan Ilir district, was arrested after he rallied in front of the police headquarters in January.

The demonstration was to show outrage that written warnings, rather than jail sentences, were handed to six police officers who were suspects in a shooting at the Cinta Manis sugar plantation last year, which left one teenager dead and three people injured.

The police officers – identified as Adj. Sr. Comr. Deni Darmapala, Comr. Awang Hariono, Comr. Riduan Simandjuntak, Comr. Barliansyah, Adj. Comr. Yuskar Effendi and Adj. Comr. Agus Selamat – were initially named as suspects in an internal police investigation following a clash between locals and police at the plantation in Ogan Ilir district on July 27, 2012, which left 12-year-old Angga Bin Darmawan dead and three more injured from the Limbang Jaya village.

Both Anwar and Dedek have been detained since February, which means they only need to stay in prison for four more months. Prosecutor Mahcsun said he would file an appeal. Previously the prosecutors demanded two and a half years in prison for both activists.

Haris Azhar, coordinator of the Commission for Missing Persons and Victims of Violence (Kontras), said the judges' decision was disheartening and would set a bad precedent for activists in the future.

"We reject the verdict and we demand the court to annul it. Anwar is human rights fighter who has helped a lot people in fighting for their rights," he told the Jakarta Globe on Thursday.

Haris said Anwar, who was seriously injured during the rally, was only assisting farmers who have been long frustrated by the land dispute.

"The police didn't catch or punish people who attacked him. This is obviously a double standard – the police are protecting the company's interest," he said.

Following the clash on January 30, Anwar and 24 other people were arrested. Three people, including Anwar, were declared suspects.

Walhi has claimed that the police have used torture and excessive force in handling the protestors. A picture of Anwar with his head bleeding spread quickly over social media, prompting Walhi to start the petition at www.change.org/FreeAnwar.

As of February 2, more than 7,000 people had signed the online petition, demanding Anwar to be released.

The sugar plantation there has been a source of tension since state-owned plantation company PTPN VII forcefully evicted 22 villages in the district to set it up in 1982. Rights activists say PTPN VII used security forces to pressure residents into giving up their farms, while failing to provide adequate compensation for the land.