WASHINGTON (Reuters) - President Barack Obama will launch a trade complaint against China over unfair government backing of its auto industry, a White House official said on Sunday.

Obama will announce on Monday that he is initiating a case against China at the World Trade Organization over allegedly illegal subsidies for automobiles and auto parts during a campaign tour of Ohio, the official said.

Ohio relies heavily on the auto industry and is a politically important swing state.

Obama has said Beijing is abusing trade laws by imposing more than $3 billion in duties on U.S. auto exports.

(Reporting By Jeff Mason and Mark Felsenthal; editing by Christopher Wilson)