NEW DELHI (AFP) - Doctors in India have removed the skeleton of a foetus that had been inside a woman for 36 years in what is believed to be the world's longest ectopic pregnancy, a doctor has said.

The 60-year-old woman became pregnant at the age of 24 but suffered a miscarriage because the foetus had been growing outside of her uterus, the doctor told AFP on Monday.

The woman, from a poor rural area in central India, was "terrified" of having surgery at the time to remove the remains of the foetus, and instead sought medication for the pain at a local clinic.

Although the pain gradually subsided, it returned years later, forcing the woman to seek medical help at a hospital in western India, Dr Murtaza Akhtar said.

"She came to us complaining of pain in the abdomen," said Akhtar, head of surgery at the N.K.P. Salve Institute of Medical Sciences in the city of Nagpur.

Doctors felt a lump on her lower right abdomen and feared it could be cancer - but further tests and scans revealed a calcified mass.

"Once we saw the scans, our first reaction was 'what are we dealing with'? It was actually a matured skeleton encapsulated in a calcified sac," Akhtar said.

"A 60-year-old woman with a foetus lying in her abdomen for 36 years is a medical marvel. It's something we had never heard about."

The doctors searched medical literature and discovered a woman in Belgium who had retained the remains of a foetus for 18 years following an ectopic pregnancy, the longest they could find on record.

An ectopic pregnancy occurs when the egg implants outside the uterus, usually in the fallopian tubes.

A team of doctors in Nagpur successfully performed surgery to remove the mass that was lodged between the woman's uterus, intestines and bladder.

"She was shocked when she first got to know what had happened. But she is fine now and is recuperating," Akhtar said.