The Iranian daily Etemaad says the creature is believed to have grown from larva to an adult frog inside her body.

While it is unclear how this could have happened, the paper carries quotes from medical experts who say there are human characteristics to the animal.

It has been speculated that the woman, who has not been named, unknowingly picked up the larva while she was swimming in a dirty pool.

The woman, from the south-eastern city of Iranshahr, is a mother of two children.

The "so-called frog", as the newspaper puts it, has yet to undergo precise genetic and anatomic tests.

But it quotes clinical biology expert Dr Aminifard as saying: "The similarities are in appearance, the shape of the fingers and the size and shape of the tongue."

Medical history recounts stories of people who believed they had frogs - or even lizards or snakes - living and growing in their bodies.

One of the most famous was the 17th Century case of Catharina Geisslerin, known as "the toad-vomiting woman" of Germany.

When she died in 1662 doctors are said to have performed an autopsy, but found no evidence animals had ever lived inside her body.

BBC Monitoring, based in Caversham in southern England, selects and translates information from radio, television, press, news agencies and the Internet from 150 countries in more than 70 languages.