The Vietnamese foreign ministry’s deputy spokesman Doan Khac Viet said they will protect their citizens’ rights, VnExpress reported.

Doan  said that after they were notified of the arrests and seizure, the ministry instructed the embassy in Malaysia to contact local authorities.

They also requested for the fishermen to be “treated humanely”.

“The embassy would also request Malaysia to provide evidence related to the fishing vessels on the basis of which the Vietnamese authorities can then investigate the incident and punish the fishermen if any violations were found,” he was quoted as saying by the Vietnamese portal.

Some 32 crew members on board the four vessels were detained on April 26. It is alleged that they did not have any personal documents on them nor fishing licences.

One of the vessels was said to have been flying the Jalur Gemilang, while another ship possessed both Vietnamese and Malaysian vessel numbers.