A South Carolina woman who admitted to drowning her two sons 30 years ago was denied parole after her first hearing on Wednesday.

Susan Smith, 53, was convicted of killing her boys by strapping them into their car seats and letting the vehicle roll into a lake. The 1994 case captivated many.

Smith, who has spent 30 years behind bars, apologised to the seven-person parole board for the murders and requested to be freed.

“I know what I did was horrible,” she said. “And I would give anything so I could change it.”

The father of her children and the prosecutor of the case also spoke to the board, asking them to keep her behind bars.

David Smith, the boys’ father, told the parole board that 30 years in prison was not a severe enough punishment for Smith.

“That’s only 15 years per child, her own children,” he said. “That’s just not enough.”

Prosecutors argued during the trial that Smith killed her three-year-old Michael and one-year-old Alex after a man with whom she was having an affair told her that her sons were the reason that the pair did not have a future together.

Prosecutor Tommy Pope said Smith had made a “horrible, horrible choice to choose a man over her family”.

“Susan has always focused on Susan,” he said.

During the trial, Smith initially said she was carjacked at late at night and that a man drove away with her car. While she pleaded publicly for the safe return of her sons, they were at the bottom of a nearby lake.

But ultimately she confessed to the crime.

Defence lawyers said she suffered a mental breakdown and wanted to die with her children but left the car at the last minute.

Smith was convicted of murder, but under South Carolina law at the time she was eligible for a parole hearing every two years after serving 30 years in prison.

Smith would need two-thirds of board members who are present to vote in her favour to be freed, according to the state Department of Probation, Parole and Pardon Services.