Malaysian police have made their first arrests since Malaysia began enforcing bans on its citizens illegally crossing the border into Thailand from Kelantan state.
They detained two Malaysians and two Thai nationals attempting to cross the Golok river to Narrathiwat.
Kelantan deputy police chief Ayob Khan Pitchay announced on Sunday the arrest of the four men at separate locations in Rantau Panjang, a border town opposite Sungai Kolok district in Narathiwat, according to Malaysia's Bernama news agency.
The names of the two Thais were not released. Malaysian police said they were aged 33 and 50 years. They were under investigation for illegal entry.
The two towns are separated by the Golok River, which forms the border in that area.
Many Thais and Malaysians living along the river use illegal piers to cross the border, often visiting relatives.
Malaysian police earlier declared that from Dec 1 they would begin enforcing bans on their people using illegal crossings, part of a campaign against smuggling and other border crime.
Malaysia originally planned to deploy a special police force at the border between Kelantan and Sungai Kolok on Dec 1. The police deputy chief said the deployment was deferred to Jan 1, Bernama reported.
The Thai consulate-general in Kota Bharu, the state capital, has warned Thais of strict law enforcement at the border. It strongly advised Thais to enter the state only through legal checkpoints, using a passport or a border pass.