LONDON/PARIS, Nov 30 (Reuters) - The head of Qatar Airways on Tuesday called on Airbus to admit that it had a problem with flaws on the surface of its A350 jets and ruled out buying freighter planes from the European company, effectively handing a potential deal to rival Boeing (BA.N). Chief Executive Akbar Al Baker confirmed that the Gulf airline had grounded 20 of the long-range A350 jets in a months-long dispute over paint and other surface damage that has also prompted the airline to halt further deliveries. "Qatar Airways cannot sit with its arms folded and legs crossed. We need to solve it. Airbus has made a very large dent in our widebody operations," Al Baker said. "It is a serious matter; we don"t know if it is an airworthiness issue; we also don"t know that it is not an airworthiness issue. The real cause of it has not been established by Airbus," he told The Aviation Club in London. "Now they have, at last, accepted that there are other airlines, several of them that have the same condition." A Reuters investigation published on Monday found that at least five other airlines had raised concerns over surface flaws since the A350 entered service and that in at some cases damage extended below paint to a layer of lightning protection. Airbus, which until recently maintained that the problem was confined to Qatar Airways, has said the plane is safe and that it understands the root cause of the problem. read more An Airbus spokesperson said it had nothing to add to earlier statements. On Monday, Airbus confirmed it was looking at updating the lightning system to a more flexible material called Perforated Copper Foil, a move first reported by Reuters. "They have acknowledged that they are working to find a solution, which means they still don"t have a solution," Al Baker said on Tuesday, adding the Airbus problems were worse than current production flaws faced by the Boeing 787 (BA.N). "And they don"t have a solution because they still don"t know why it is happening. You know it is always better when there is a problem to admit, not to put your customer in a corner and blame them for something which is actually your own problem." NO AIRBUS FREIGHTER DEAL Al Baker suggested that any plans to replace the A350 anti-lightning system, known as Expanded Copper Foil, with a new material may require certification. Airbus declined comment. Qatar"s national carrier has said it is progressively grounding its 53 A350s on orders from its regulator, until reasons for what witnesses describe as the blistered and pock-marked appearance of some the aircraft can be confirmed. The Qatar Civil Aviation Agency has declined comment. The European Union Aviation Safety Agency has said that there is "no indication that the paint and protection degradation" affects the structure or safety of the A350. So far Qatar Airways is the only airline to ground the jets. Al Baker was also asked about a possible purchase of Boeing 777X freighter aircraft to replace the airline"s current fleet of 34 dedicated cargo planes, following his recent comments that Qatar was looking at an "attractive proposition from Boeing". Asked if this would close the door on buying the new A350 freighter, he said "yes". Asked if the order could reach around 50 freighters, he said nearly, without giving more details. A spokesperson for Boeing (BA.N) declined comment.