JAKARTA • An Indonesian palm oil executive has been arrested for allegedly ordering the killing of two activist journalists who were mediating a land dispute between his company and local residents, police said yesterday.

Mr Maraden Sianipar's body was found last week in a ditch near a palm plantation in Labuhan Batu in 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.

The North Sumatra authorities said yesterday they had arrested businessman Wibharry Padmoasmolo for allegedly masterminding the plot by paying nearly US$3,000 (S$4,080) to four men to commit the killings.

Padmoasmolo owns a firm that produces palm oil - a widely used vegetable oil found in everything from soap to chocolate - which was in a dispute with locals that the two victims were advocating for, police said. The killings were aimed at stopping the pair's involvement, said the authorities, who added that Padmoasmolo has denied owning the firm during questioning.

In all, five people have been arrested in connection with the murder plot and police said they are still searching for several more suspects still at large.

"We are looking for the three, while the five other suspects have been detained for further questioning," said North Sumatra police chief Agus Andrianto.

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

A friend of Mr Siregar said they 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 dispute.