The Singapore Civil Defence Force (SCDF) has discontinued the underwater search operation for a missing boatman of the river taxi that caught fire near Esplanade's Outdoor Theatre on Tuesday evening.

A SCDF spokesperson said that they resumed a "surface search" on Wednesday morning after they stopped the underwater search at around midnight on Tuesday.

Both the SCDF DART rescuers and firefighters, along with the PUB staff, are part of the operation at the Singapore River.

The missing boatman, who was said to be in his 30s, was the only person on the boat at the time of the incident. He jumped off his bumboat after it caught fire on the Singapore River.

The search methods included point diving at a depth of about 4 metres and employing a circular search pattern from the place where the man was last seen, followed by the search team moving in a grid formation.

The SCDF team said poor underwater visibility was a big challenge. The DART rescuers had to search through the deep silt of the river bed.

SCDF said there were no reports of any other missing people or injuries from this incident.