SINGAPORE - Her eyes were brimming with tears at her son's death, but Madam Shakina Mohamed, 48, was also beaming with pride at Mr Mohammad Firdaus Jasni's last act that saved a colleague's life.

The commercial diver, 27, the eldest of six children, died on the job while in the waters off Pulau Sebarok - an island south of Sentosa - on Saturday (June 23).

He was believed to have been with a team of seven other commercial divers working on concrete piles underwater.

Speaking to The Straits Times on Sunday after her son's body had been taken to the burial grounds, Madam Shakina, a civil servant, said Mr Firdaus' company manager had told her about his courageous act before the fatal accident.

He was believed to have pushed a fellow diver out of harm's way when a concrete pile fell, and he was hit by it.

The Ministry of Manpower (MOM) said Mr Firdaus and another diver were installing brackets onto a concrete pile underwater, when he was struck by a concrete pile.

The police received a call for help at 5.13pm on Saturday and are investigating the unnatural death.

ST understands that a crane was used to lift the structure to free Mr Firdaus, before he was taken unconscious to the hospital, where he died from his injuries.

Said Madam Shakina: "Although he risked his life, I feel proud. It could have been two people hurt.

"He had a big heart. I have no words for the sudden loss, but I know he would go out of his way to help others."

She said her son had been a commercial diver for about two years, and had worked at Jurong Island before that. He had recently rejoined the underwater diving contractor firm he was with.

The mother and son were close, and Madam Shakina had been worried when Mr Firdaus, who enjoyed sports and the outdoors, started commercial diving as the job was physically taxing and she had heard it could have long-term ill effects on his health.

"But he was so passionate about it, so I let him do it. He just got the results of his health check-up last week, and everything was all right, so we didn't expect anything to go wrong."

Around 200 family members and friends gathered to send Mr Firdaus off on Sunday evening at the family's flat in Jurong West.

"I'll dearly miss the little things, the small hugs he gave or the way he'd come into my room and massage my feet," said Madam Shakina.

She said Mr Firdaus was filial and contributed to the family's expenses.

He also took care of his younger siblings and she used to pack lunch for him every day.

"His manager said my son never joined the others for lunch because he would tell them that his mother had packed food for him.

"It's a small thing, but I never knew how much he appreciated it until I heard it from someone else."

She added: "Although he was never in a high position and is now far away, I'm very proud of him."

Mr Firdaus was working on a project developed by Vopak Terminals Singapore.

The project's occupier is HSL Constructor. All work at the site has stopped and MOM is investigating.

Vopak Terminals said Mr Firdaus was from a firm that was subcontracted to help in demolition works at the site at Sebarok Jetty 2.

It added that Mr Firdaus and another diver were installing an underwater clamp in preparation for pile cutting when a nearby pile collapsed and hit him.

"We, jointly with our main contractor and his employer, are providing his family with all possible aid and assistance they need during this difficult time. Authorities have been involved, we are working closely together," said Vopak Terminals, adding that it has started a thorough investigation to find the "root cause" of the incident.

On May 5, freelance commercial diver Jake Seet went missing as he was conducting underwater operations for a vessel near Sentosa.

His body was found on May 7.