He was a competitive cyclist who had taken part in numerous regional competitions for more than 20 years.

But retired businessman Denison Seah, 57, was killed in an accident on Sunday morning while on a casual ride in Chiang Mai, Thailand, where he had lived for the past three years.

The Singaporean was cycling with his Thai girlfriend when he was reportedly hit by a five-tonne lorry on a two-lane road.

Mr Seah's Thai friend, who wanted to be known only as Mr Justin, 55, said yesterday that the couple were on a popular cycling route in the Hang Dong district, heading from his home in the town of Mae Hia to the Samoeng district, when the accident happened.

"He usually woke up at 5am on weekdays to train, but he did not have training on Sundays," said Mr Justin, a powerboat race director. "He died while he was being taken to the hospital after the accident."

He added that Mr Seah was a good racer whose main interest was in road cycling, and that he had many cycling buddies in Thailand and Singapore.

Mr Seah's daughter Christine, 27, a dog groomer, said that Mr Justin called her at about 11.30am on Sunday with the news that her father had been in a bad accident.

"He said that my dad was on the way to the hospital and asked me to go to Chiang Mai quickly. He then hung up abruptly."

As she was struggling to cope with the shocking news and the lack of information, he called again after five minutes.

"That was when he told me that my dad had passed away," she said.

Pictures of the accident circulating on Thai social media showed a cyclist believed to be Mr Seah lying in a pool of blood, and a distraught woman, believed to be his girlfriend, kneeling beside him on the road.

Miss Seah said she and her uncle would be flying to Thailand yesterday to bring her father's body back for a funeral in Singapore.

She said she was still unclear on the exact details of what happened, but added that her father moved to Chiang Mai about a year after her mother died in 2014.

"We were not always on the best of terms, and I last saw him two years ago when he came back to Singapore for a while," said Miss Seah.

"He was happy there. This was really sudden and unexpected, but I guess the comfort we have is that he went out doing what he loved most."

She said that she regretted not reaching out to him when she had the chance.

"We are both the type who aren't open with our feelings and did not know how to show affection.

"I made the mistake of not talking to him more, not telling him that despite all our fighting and dramatics, that I loved him very much and was thankful that he had raised me to be the person of extreme resilience that I am today.

"Rest in peace, Dad. I am sorry I was not there."