More than 7,000 people have signed an online petition demanding the National Police Chief and South Sumatra Police release an activist arrested during a protest rally held by farmers and environmentalists on Tuesday.

Arief Aziz, the communication director for the online petition website change.org, said in a statement on Friday that more than 7,000 people had demanded the release of Anwar Sadat, the director of the South Sumatra chapter of the Indonesian Forum for the Environment, which is also known as Walhi.

The arrest came after Anwar, along with several farmers from the village of Betung in the Ogan Ilir district, were rallying in front of the police headquarters. The protesters were demonstrating against the state-owned plantation firm PTPN VII Cinta Manis over a land dispute.

Anwar and 24 other people were initially arrested before 22 of the protestors were released. 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.

Walhi added that Anwar was currently being treated for his injuries at the Bhayangkara Hospital in South Sumatra.

One person who signed the petition, Nidya Pramiella Gayatri, expressed her frustration over the excessive use of force by police. "It is their [police] job to protect and serve the people, and for them to commit such an act of violence is unjustifiable," she said.

Usman Hamid, a human rights activist from the Public Virtue Institute, welcomed the move by the South Sumatra Police to release most of the arrested protestors.

The activist said he had received a positive response from the South Sumatra Police chief after discussing the possibility of delaying the detention of Anwar and the other suspects.