A new strain of norovirus has been discovered which scientists warn could cause a severe epidemic of gastroentiritis this winter.

The highly infectious Sydney 2012 mutant virus was identified last March, and was found to be one of the GII.4 strains of norovirus which are responsible for epidemics and pandemics.

Members of the UNSW research team worked out the complete genetic sequence of the virus and found it was a combination of two strains originating in Holland and Japan.

The strain has so far been responsible for 1.2 million cases of gastroenteritis in the UK, and is expected to be the dominant strain in the Australian winter.