Antananarivo - A super-sized rat, about the size of a six-month baby, has been discovered in southern Madagascar, local media reported Thursday.

The 7.5-kilogramme "rattus norvegicus" or brown rat was found in the Mandena nature reserve in the tropical south of the vast Indian Ocean island, L'Express newspaper said.

The biggest specimen of this species of rat found to date was 1.5 kilogrammes, according to the doctor responsible for pest control in Madagascar's health department, Sahondra Ramiakajato.

According to the report, a population of unusually large rats was found near the town of Ambatondrazaka in the past but they were far smaller in size than the latest catch.

Rodent specialists are trying to ascertain where the rat came from from.

Some have speculated it might have escaped from a laboratory, where it might have been fed an unusual diet that could explain its girth. (dpa)