India has announced a major breakthrough by its scientists who have unveiled a low-cost vaccine against a deadly virus that causes severe diarrhoea which kills about half-a-million children worldwide every year.

The vaccine, Rotavac, against the deadly Rotavirus is actually the culmination of 25 years of work, involving multi-institution and multi-country collaboration, local media reported. However, it is yet to be approved by Indian drug authorities for mass production of the vaccine.

"This is an important scientific breakthrough against rotavirus infections, the most severe and lethal cause of childhood diarrhoea, responsible for approximately 100,000 deaths of small children in India each year," K. Vijaraghavan, the Secretary of India's Department of Biotechnology, told the media in the national capital Tuesday.

He added, "the clinical results indicate that the vaccine, if licensed, could save the lives of thousands of children each year in India."

The official said that the one US dollar oral vaccine was ready for production.

International pharma giants like GlaxoSmithKline and Merck produce similar vaccines but each costs around 1,000 Indian rupees.

The vaccine will be produced by Bharat Biotech Ltd, based in the southern Indian city of Hyderabad.

Sheela Panicker, a company spokeswoman, said the oral vaccine will also be made available to other developing countries. "We have pledged it to the government and the vaccine will be also be supplied to developing countries through a UN agency," she was quoted as saying.