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Scientists have been left shocked by the surprising appearance of hundreds of methane vents off the US East Coast.

More than 500 vents have been found where methane is seeping into the ocean.

And there is concern that these increased amounts of gas could be caused by global warming.

A large number of methane vents have been found off the US East Coast. The findings suggest such leakage is far more widespread in the Atlantic than thought. Here methane is seen streaming from the seafloor at a depth of about 1,400 feet (425 metres) offshore from Virginia

The study published in Nature Geosciences was carried out by researchers from Mississippi State University, the US Geological Survey (USGS) and other institutions.

The research suggests that natural methane leakage from the seafloor is far more widespread in the US Atlantic than previously thought.

In total more than 570 seafloor cold seeps were observed between Cape Hatteras, North Carolina and Georges Bank, Massachusetts.

Cold seeps are areas where gases and fluids leak into the surrounding water from sediments on the seafloor.

The seeps were found on the outer continental shelf and the continental slope of the eastern US.

Previously, only three seep areas had been identified in this area - making the findings a dramatic increase on what was known before.

'Widespread seepage had not been expected on the Atlantic margin,' said Adam Skarke, the study's lead author and a professor at Mississippi State University.

'It is not near a plate tectonic boundary like the US Pacific coast, nor associated with a petroleum basin like the northern Gulf of Mexico.'

In total more than 570 seafloor cold seeps were seen between Cape Hatteras, North Carolina and Georges Bank, Massachusetts (shown in this map). The study, published in Nature Geosciences, was carried out by researchers from Mississippi State University, the US Geological Survey (USGS) and other institutions

The seeps were found on the outer continental shelf and the continental slope of the eastern US (illustration shown). Previously, only three seep areas had been identified in this area - making the findings a dramatic increase on what was known before

The location of the seeps and knowledge of the underlying geology suggests the leaking methane is being produced by microbial processes in shallow sediments.

At depths of more than 2,000 feet (600 metres) in some places, the seeps are too deep to release methane directly into the atmosphere.

However, there is the danger that if the methane stays in the water, it could oxidise into carbon dioxide.

This can increase the acidity of ocean waters and reduce oxygen levels, which can be harmful to marine life.

While not directly pointing a finger at climate change, the researchers indicate that global warming could be the cause of the problem.

'Warming of ocean temperatures on seasonal, decadal or much longer time scales can cause gas hydrate to release its methane, which may then be emitted at seep sites,' said Dr Carolyn Ruppel, study co-author and chief of the USGS Gas Hydrates Project.

'Such continental slope seeps have previously been recognised in the Arctic, but not at mid-latitudes. So this is a first.'

In this image push cores are used to collect samples of the sediment found near a seep site, allowing investigation into the biological, chemical and physical make up of the bottom during the Deeptwater Canyons 2013 Expedition, from which some of the findings were made