PARIS, July 29 (Reuters) - Airbus (AIR.PA) said its board had backed plans for a new freighter version of its A350 passenger jet as it seeks to break rival Boeing"s (BA.N) dominance of the air cargo market. Chief Executive Guillaume Faury said that following the green light, "we are enhancing our product line with an A350 freighter derivative, responding to customer feedback for increased competition and efficiency in this market segment." Plans by the European firm to challenge Boeing"s control of the freight market with a version of its lightweight A350 wide-bodied jet were first reported by Reuters in March. read more The A350 freighter"s formal launch is certain to trigger a response from Boeing after Chief Executive Dave Calhoun on Wednesday listed developments including "I hope in the relatively near term" a freighter version of the 777X.