The UN Food and Agriculture Organization said in a statement Monday a mutant strain is spreading across parts of Asia, and there could be a spill-over to humans.

　　However, it said at this stage, there's no need for any alarm.

　　A mutant strain of H5N1, which can apparently sidestep defenses of existing vaccines, is spreading in China and Vietnam, it said.

　　It said the variant of the virus appears able to side step Vaccines.

　　The UN is concerned the new form of the virus could spread to Cambodia, Thailand and Malaysia, as well as the Korean Peninsula and Japan.

　　"Wild birds may introduce the virus, but people's actions in poultry production and marketing spread it," said FAO's chief veterinary office Juan Lubroth in urging greater preparedness and surveillance, according to media reports.

　　Outbreaks of the virus peaked in 2006 before it was eradicated from most countries.