WASHINGTON -- Researchers using mail-order materials and a genetic code have synthesized the poliomyelitis virus in the laboratory according to a study in the journal **** Science ****'s Friday issue.

The synthetic virus was virtually indistinguishable from the original, and first paralyzed, then killed mice injected with it, according to the study at the state University of New York at Stony Brook.

"The potential for virus synthesis is an additional important factor for consideration in designing the closing strategies of the Poliovirus Eradication Campaign," the researchers led by Eckard Wimmer said in the study, warning that a synthetic virus would be valuable as a bioweapon if mass vaccination stops and immunity to the disease is lost.

In an accompanying article, **** Science **** said biologists disagreed over how easy it would be to create bioweapons or synthesize bulkier viruses such as smallpox.

"It is a little sobering to see that folks in the chemistry lab can basically create a virus from scratch," AFP quoted James Leduc of the Centers for Disease Control and Prevention in Atlanta, Georgia, as saying.

The World Health Organization last month certified Europe as free of polio, marking a major step toward the eradication of the disease by 2005.

Europe is the third geographical region to certify that it has had no indigenous cases for three years, following the Americas in September 1994, and the Western Pacific in October 2000.

Ten countries in the world are regarded as polio endemic, several of them countries in conflict where vaccination campaigns have been disrupted.

Conflict in four of the countries in recent years -- Angola, Afghanistan, Sudan and Somalia -- have hampered access to children.

The other polio-endemic countries are Egypt, Ethiopia, India, Nigeria, Niger and Pakistan.