Elizabeth Poblete came 12th in her category at the Beijing Olympics

Chilean Olympic weightlifter Elizabeth Poblete has given birth to a baby boy during a training session, without having known she was pregnant.

Ms Poblete, 22, who lives in Brazil, said she had felt unwell but had no idea she was expecting a baby.

The boy was three months premature and was taken to hospital with his mother, where he remains in intensive care.

The hospital in Sao Paulo denied reports it forced Ms Poblete to leave after she was unable to pay for care.

Ms Poblete began to feel unwell during training on 8 December, as she was preparing to take part in a competition.

Shortly after, she gave birth to a baby weighing only 1.15kg (2.54lbs) and measuring about 34cm (14 inches).

The head trainer at the gym, Horacio Reis, said the birth had been "a surprise".

"A week ago I acted as a judge in a competition in Chile and this girl was competing. All went well and she won the competition," the AFP news agency quoted him as saying.

"I could see she was a big girl, round and strong. That's all I noticed."

Mother and child were both taken to hospital in Sao Paulo but Ms Poblete has since been discharged, reportedly telling local media she could not afford to continue receiving treatment.

Ms Poblete came 12th in the 75kg women's category at the 2008 Olympics in Beijing.