Authorities in Thailand have launched an investigation after a second fatal explosion on a tanker in three weeks.

The 3,500-dwt Ampar 8 (built 2007) was hit by a blast at Samut Prakan on Sunday, killing a crew member and injuring four others.

The transport ministry has ordered the marine department to investigate why the tanker, which was carrying 3.2m litres of crude, exploded and caught fire, The Nation reported.