Joe Biden won the Arizona Democratic primary over Bernie Sanders, giving him a sweep of the three US states which voted on Tuesday, TV networks said.

File photo: VCG

CNN and NBC both projected the 77-year-old former vice president as the winner in Arizona over the 78-year-old senator from Vermont.

With 56 percent of precincts reporting in Arizona, Biden led Sanders by 42.6 percent to 30.3 percent, according to New York Times figures.

Biden also won primaries in Florida and Illinois on Tuesday to open up a commanding lead over Sanders in the race for the Democratic presidential nomination.