It comes after both Ryanair and Aer Lingus refused to comment last week when asked if they were lobbying the Government to have the rules changed.
The joint letter, which is also signed by the governments in France and the Netherlands, points out that European Commission Regulation 261/2004 and "its obligation to reimburse cancelled tickets in cash, if the passenger so decides, places airlines in a difficult situation where they are facing a serious cash flow challenge".
Comment: Are citizens not facing 'serious cash flow challenges'?
The letter calls for the rules to be changed temporarily to allow airlines to issue vouchers instead of refunds.
The joint letter states:
Comment: See also: