Four people were injured in an Islamist separatist bomb attack at a market in southern Thailand.

A motorcycle rigged with explosives was detonated near a checkpoint in Tha Phraya Sai in Narathiwat province, wounding four individuals caught in the blast on May 6 evening.

Police Colonel Pratchaya Baite, superintendent of the Mueang Narathiwat Police Station, said officers were notified of the explosion at 9:35 pm.

A firefighting team was dispatched to extinguish the blaze in the vicinity, followed by an explosive ordnance team that investigated the motorcycle bomb.

Officials said an improvised explosive device was hidden under the motorcycle's sidecar.

Two volunteer defence corps staff, Atsaree Hayeeawae and Hafit Sa-ae, suffered head, ear, and chest pains, while two civilians, Zaherah Gaji and Nurfazela Bueraheng, had facial wounds and were struck by shrapnel.

They were taken to the Naradhiwas Rajanagarindra Hospital for treatment.

Police Colonel Pratchaya said: 'We have cordoned off the scene and blocked traffic so the site can be investigated. An explosive ordnance team is also scouring the area for possible additional explosives hidden nearby. We aim to track down whoever planted the bomb so they can be prosecuted as soon as possible.'

Islamist separatist terror attacks target the three southernmost provinces of Thailand - Yala, Pattani and Narathiwat - next to the border with Mulsim neighbors Malaysia. Thai state employees and infrastructure are often hit while attacks on civilians are rare.

Officials believe the conflict dates to a deal in 1909 that the British Empire struck to incorporate the Muslim region into the Siamese mainland.

The region's culture is more similar to Malaysia and dramatically different to Buddhist Thais causing decades of tension that lead to the emergence of separatist groups fighting for independence in the 1960s.

The struggle has continued ever since with more than 7,344 people killed and 13,641 injured between January 2004 and March 2022.

The British Foreign & Commonwealth Office warns against all but essential travel to the region while Canada's government warns its nationals to 'avoid all travel' to the three provinces.

Tourists rarely venture into the region.