Polish Olympian put her Tokyo silver medal up for sale to save the life of a kid who needs a $250,000 heart operation.

Maria Andrejczyk, aged 25, had to overcome bone cancer to resurrect her javelin career, after failing by 2cm to land a medal at the 2016 Rio Olympics.

It led to an emotional scene as she stood on the podium in Japan, after which she sought a cause to support from social media followers.

"The true value of a medal always remains in the heart," she told Polish TV, according to The Times.

Andrejczyk revealed on Wednesday in a Facebook post that she had auctioned off her medal for eight-month old Miłoszek Małysa, who had a serious heart defect.

"He already has a head start from Kubus -- a boy who didn't make it in time but whose amazing parents decided to pass on the funds they collected," she wrote in Polish on her page.

"And in this way, I also want to help. It's for him that I am auctioning my Olympic silver medal."

It led to another medal ceremony of sorts for Andrejczyk. A Polish chain store named Żabka won the auction and told her she could keep the medal.

"We were moved by the beautiful and extremely noble gesture of our Olympian," a spokesperson said.