Bangkok, Dec 6 (IANS): An explosion at a railway track in Thailand's Songkhla province on Tuesday killed at least three people and injured four others, authorities said

According to the State Railway of Thailand (SRT), the incident occurred at 6.24 a.m., and the blast hit a section of the track where repair work was ongoing, reports Xinhua news agency.

The victims were three SRT officials.

The section was only 200 metres away from the point where another explosion occurred on December 3, which derailed a freight train.

Songkhla Governor Jessada Jitrat visited the scene to assess the situation in order to prevent the reoccurrence of such attacks.

Meanwhile, a bomb disposal squad and security officials have launched investigations into Tuesday's explosion.

According to local media, the attack on December 3 was believed to be carried out by the southern insurgents.

Separatist movements and organised crimes have occurred periodically in southern Thailand for decades.