MEDAN, INDONESIA (AFP) - Two men have been arrested in connection with the brutal murder of a pair of Indonesian activist journalists who were mediating in a land dispute between a palm oil company and locals, the authorities said on Tuesday (Nov 5).

Mr Maraden Sianipar's body was found last week in a ditch near an oil palm plantation in Labuhan Batu, an eight-hour drive from the capital of North Sumatra province.

Police found the remains of his colleague, Mr Maratua Siregar, in the same area a day later.

Both had been stabbed multiple times.

On Tuesday, police said they had arrested two suspects and were seeking four more, adding they could face the death penalty if charged and found guilty of murder.

"The motive was revenge and was linked to the palm plantation land dispute," local chief detective Jama Kita Purba told AFP.

"We are still investigating the details," he added.

Mr Sianipar and Mr Maratua worked together for a local online news portal before going freelance in 2017.

A friend of Mr Siregar said the victims had recently become known for their activism in land disputes - a common source of conflict across the resource-rich South-east Asian archipelago.

The friend said Mr Siregar was active in an organisation that advocated for residents in the land dispute.

Indonesian journalist associations condemned the deaths and demanded the authorities investigate the cases thoroughly.

Many cases of violence against journalists in Indonesia go unsolved, according to the Independent Journalists Alliance, which has reported at least two dozen cases this year alone.

Indonesia is ranked 124th out of 180 countries on the 2019 World Press Freedom Index published by Reporters Without Borders.