A Singapore Civil Defence Force officer who was jailed for pushing a man into a fire station pump well owned up right away when the station commander asked how the full-time national serviceman had fallen into the well, but said he had been instructed to do so by another officer.

Recounting the events in the immediate aftermath of the fatal incident on May 13 last year, SCDF Staff Sergeant Al-Khudaifi Chang, 26, said yesterday that Muhammad Nur Fatwa Mahmood had admitted to it when station commander Major Huang Weikang asked how Corporal Kok Yuen Chin had fallen in.

"Fatwa raised his hand to answer the question. He said he was the one that pushed Cpl Kok in and Farid was the one who told him to push," said Staff Sgt Al-Khudaifi, taking the witness stand on the first day of trial for Mohamed Farid Mohd Saleh, for instigating Nur Fatwa to make the push.

Farid, 35, a First Warrant Officer, is contesting the charge of abetting a rash act causing death.

Cpl Kok, 22, drowned after falling into the 12m deep well at Tuas View Fire Station. Five were charged for their involvement.

Last October, Nur Fatwa was sentenced to one year and four weeks in jail for pushing Cpl Kok into the well and telling another officer to delete footage of the incident. He is currently under home detention.

Recounting details of what took place at the station after the incident, Staff Sgt Al-Khudaifi said Fatwa had asked him and other officers just as they were about to give their statements to the police if they had heard Farid instruct him to push Cpl Kok into the pump well.

"I told Fatwa that I didn't hear such a thing. I don't remember what the others told him," said Staff Sgt Al-Khudaifi, noting that there was a lot of commotion around the well just before Cpl Kok fell in and he did not pay attention to the conversations around him.

Before the incident, most of the officers on duty at the fire station had gathered in the control room for a cake-cutting ceremony to celebrate Cpl Kok's impending completion of National Service.

According to an agreed statement of facts that was admitted in court on Monday, some officers had started shouting "kolam, kolam", which means "well" in Malay, while in the room.

Some officers then lifted Cpl Kok and carried him out of the room to the pump well across the yard.

Court documents said Farid did not see who did this or how it happened, and he remained in the control room to have a second helping of cake and talk to rota commander Kenneth Chong Chee Boon.

As a result, Farid did not hear the protests that Cpl Kok had made while he was carried to the well, and he only joined the group around the pump well when Cpl Kok was back on the ground.

The trial continues today, during which Staff Sgt Al-Khudaifi will be cross-examined. Nur Fatwa is expected to take the stand in the afternoon.

Concurrently, Chong, 38, a Lieutenant, and Nazhan Mohamed Nazi, 40, a First Senior Warrant Officer, who were both in charge of the station on the night of the incident, are also in the midst of an ongoing trial. They are each contesting a charge of aiding a rash act that caused grievous hurt by illegal omission.

The fifth officer, Adighazali Suhaimi, 33, a Staff Sergeant, was jailed a month in December last year after he pleaded guilty to intentionally obstructing the course of justice by deleting video footage that showed Cpl Kok sitting at the edge of the pump well. He has finished serving his sentence.