Oslo, Norway - It's the Winter Olympics story that has everyone talking: a day after a Norwegian biathlete won a bronze medal and immediately confessed live on television to an affair, his ex-girlfriend has now spoken out.

Asked by Norwegian channel NRK on Tuesday to share his feelings after his bronze in the 20km individual, a teary Sturla Holm Laegreid broke down and admitted he had cheated on his girlfriend.

"Six months ago, I met the love of my life, the most beautiful and best person in the world," said the 28-year-old.

"And three months ago, I made the biggest mistake of my life and I was unfaithful," he continued.

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"These have been the worst weeks of my life," he said, adding that sport had "taken a back seat in recent days".

On Wednesday, his girlfriend, whose name has not been disclosed, responded to the drama.

"It's hard to forgive. Even after a declaration of love in front of the whole world," she wrote to the newspaper Verdens Gang (VG).

"I didn't choose to be put in this position and it's painful," she said.

She also described the actions of Norwegian biathlete Johan-Olav Botn, who won the gold medal, as "moving."

As he crossed the finish line, the 26-year-old looked up to the sky, then bent forward with his hands covering his face for several seconds, in tribute to his late friend and teammate Sivert Bakken, whom he found dead in their hotel room during a training trip in December.

Laegreid said he hoped his dramatic confession and the media attention that ensued "didn't ruin Johan's day."

"Maybe it was really selfish of me to give that interview," he told a group of reporters including AFP.

"I'm not really here mentally," he admitted.

Norway's former biathlete star Johannes Thingnes Boe said Laegreid's confession came "really at the wrong time and the wrong place".