PARIS (Reuters) - France said on Wednesday that the United States must comply with a World Trade Organisation (WTO) ruling this week against U.S. tax breaks for Boeing <BA.N>, and that failure to do so would give the EU legal basis for retaliatory measures.

The WTO said this week that a tax break from Washington state to help Boeing develop its new 777X jetliner was a prohibited subsidy, in a setback for the U.S. planemaker as it eyes victory in a parallel case against Airbus <AIR.PA>.

"The United States must quickly comply with the decision and put an end to these illegal measures," the French finance ministry said in a statement.

"If not, the European Union will have the legal grounds to adopt retaliatory measures concerning goods coming in from the United States," it added.

(Reporting by Sudip Kar-Gupta; Editing by Brian Love)