A US veteran, the only officer convicted after the mass killings in My Lai, central Vietnam, in 1968, has made a public apology to victims and their families for the first time, foreign media reported.

"There is not a day that goes by that I do not feel remorse for what happened that day in My Lai," former lieutenant William Calley told members of the Kiwanis Club of Greater Columbus, Georgia.

"I feel remorse for the Vietnamese who were killed, for their families, for the American soldiers involved and their families. I am very sorry,” he added.

Calley, 66, had long refused to grant interviews about the My Lai massacre. At the rare meeting with the media at the club, Calley finally did not deny what happened in My Lai. He earlier insisted he just obey the order.

On March 16, 1968, US soldiers conducted a raid and gunned down 504 civilians, most of them being women and children, in My Lai hamlet, Son Tinh district, Quang Ngai province.

The massacre did not become public knowledge until November 1969, when journalist Seymour Hersh revealed the story and Calley was court martialed near Fort Benning.

After a 10-month long trial, Calley was sentenced to life imprisonment, but he was freed after three years when then-US President Ricahrd Nixon intervened.

Most of soldiers in connection with the mass killings had been demobilised when the court was taking place, so they were exempt from prosecution under US law. Among 26 defendants, only Calley was convicted./.