No plea was recorded from the four after the charges were read out to them in front of Judge Musyiri Peet, Utusan Malaysia reported.

Three of the accused, Jehpa Lapi-E, 56, Arun Kaeofainok, 29, and Somphon A-Dam, 51, were charged with the smuggling of a Myanmar migrant, Mohd Belal, between August 2014 and March 2015.

The fourth accused, Amree Nasalaeh, 58, was charged with the smuggling of another Myanmar national, Zedul Islam, between February 2013 and April 2013.

All four were charged under the Anti-Trafficking in Persons and Anti-Smuggling of Migrants Act 2007 which carries a jail term of up to 15 years, a fine, or both, on conviction.

The accused were not represented while deputy public prosecutor Asyraf Kamal, Lee Jung Keong, and V Suloshani appeared for the prosecution.

July 25 has been set for the next mention of the case.

Yesterday, home minister Saifuddin Nasution Ismail said the four were among 10 for whom Putrajaya had submitted extradition requests to Thailand in January 2017.

In May 2015, police discovered 139 graves in 28 temporary camps run by a human trafficking syndicate in the jungle near the Thai-Malaysian border in Wang Kelian.

Similar graves were also found near the border in Thailand.

The victims were said to have come from Myanmar and Bangladesh in search of jobs.

In 2019, a royal commission of inquiry was held to examine the evidence linked to the transit camps and mass graves. A total of 48 witnesses were called to testify.

The inquiry held that no Malaysians were involved, whether enforcement officers or ordinary citizens. However, negligence on the part of border patrols was held to have played a part in the transit camps and mass graves.

In 2017, a former Thai army general was convicted, together with other officials and dozens of Thai nationals, for human trafficking, smuggling illegal migrants and organised crime over the discovery of mass graves on the Thai side of the border.