Underground river stretching 3,700 miles found under the Amazon

A huge underground river appears to be flowing thousands of feet beneath the Amazon, Brazilian scientists have claimed.

Valiya Hamza of Brazil's National Observatory said researchers found indications that the subterranean river is 3,700 miles long, about the same length as the Amazon on the surface.

Mr Hamza said the discovery of the possible underground river came from studying temperature variations at 241 inactive oil wells drilled in the 1970s and 1980s.

He said "thermal information" provided by the state oil company Petrobras allowed his team to identify the movement of water 13,100 feet beneath the Amazon.

The Amazon, the earth's second-longest river, is by far the largest in terms of water flow, draining a large part of South America.

The apparent underground river has been named the Hamza, honouring the head of the research team that found it.

Mr Hamza stressed that the studies indicating a second west-east drainage system for the Amazon basin were still in their preliminary stages, but said he expected to be able to confirm the subterranean flow by the end of 2014.