Controversial new research has pointed the finger at Asian vessels as being responsible for the most ocean pollution.

The University of Cape Town in South Africa said merchant shipping is probably responsible for a steep rise in the number of plastic bottles littering the world's seas.

And Asian vessels are particularly to blame, the Benzinga website reported.

It had been "widely assumed" that 80% of marine plastic waste came from the shore, but the researchers said there was little evidence for this.

The study centred on a trip to Inaccessible Island in the South Atlantic.

In 2009 scientists found 3,515 items of rubbish over a 1.1km stretch of the west coast. Last year, they logged 7,368 pieces.

Plastic bottle numbers there were up 15%.

Light waste accumulates in areas with large circulating currents, so the team tried to trace the origin of the bottles using labels etc.

Asia accounted for about 74.5% of the total, with China alone coming in at 50.6%.

But seaborne plastic rubbish from China, Taiwan, Japan and Korea is mostly swept by local currents into the North Pacific.

Mystery solved?

The question then was why so much ended up in the South Atlantic?

Researchers concluded that the bottles must have been carried out from the origin region, Asia, to a place where they could wash up on remote Inaccessible Island.

This left fishing vessels or merchant ships as the culprits.

Asian fishing fleet activity has been steady since the 1990s, but cargo shipping has increased four times since 1992.

"There is an increasingly busy shipping lane from South America to Asia, principally China," the team said.

"Merchant shipping is probably responsible for much of the recent increase," especially of Chinese bottles, it added.

Australian researchers have had very similar findings.

Their conclusions were backed up by the discovery of a large partially burned bale of plastic waste.

It was argued this could only have come from a ship's incinerator.