Scientists have successfully bred a rice variety that is salt-tolerant, which could enable farmers to reclaim coastal areas rendered useless by sea water, a Philippine-based institute said Tuesday.

The International Rice Research Institute (IRRI) near Manila said its researchers are in the process of perfecting the variety of rice that would be the most salt-tolerant ever developed before field testing it widely.

"They hope to have the new variety available to farmers to grow within four to five years," the institute said in a statement.

IRRI's media office said the new variety would offer twice the salt-tolerance as previous attempts to breed such a variety.

India and Bangladesh could potentially be the biggest beneficiaries, the IRRI said, remarking that about 20 million hectares (49 million acres) of rice farms worldwide have been affected by salinity.

The new variety was bred by crossing an exotic wild rice species found in brackish water with one cultivated at the institute.

The result is a "new rice line that can expel salt it takes from the soil into the air through salt glands it has on its leaves", the statement said.

"This will make saline stricken rice farms in coastal areas usable to farmers," said lead scientist Kshirod Jena.

"These farmlands are usually abandoned by coastal farmers because the encroaching seawater has rendered the soil useless."

Incidents such as the 2011 tsunami in Japan which flooded thousands of hectares of rice farms with sea water have spurred the development around the world of new varieties of rice that can grow in such areas.

Rice is considered one of three major domesticated crops that feed the world, along with wheat and corn, and scientists have been continuously looking to develop new varieties to increase production.