LONDON (Reuters) – British Airways proposed the closure of a major pension scheme on Thursday, angering trade unions representing some workers who have already been on strike this year in a continuing dispute over pay.

British Airways, owned by International Consolidated Airlines Group, said it had to address “the significant and growing funding deficit faced by the New Airways Pension Scheme (NAPS)”, and that under new proposals it would close the scheme.

“We will be proposing new pension arrangements that will improve benefits for the majority of UK colleagues,” British Airways said in a statement, adding NAPS, which has some 17,000 BA staff members, would be closed to future accruals but the pension benefits already earned would be protected.

However trade unions Unite and GMB said in a joint statement that the move was a “bitter disappointment”, saying they had been working to explore options to keep the scheme open.

“This announcement sadly confirms that our advice has gone unheeded and that we have been unable to convince British Airways that keeping the scheme open is the right thing to do, for both the company and its employees,” the unions said in a statement.

“Instead of certainty many will now face uncertainty as their retirement approaches.”

Separately Unite members of BA’s “mixed-fleet” cabin crew that serves long and short-haul routes have been on strike several times this year, in a long-running dispute over pay and sanctions against those taking industrial action.

In August Unite said it would suspend strike action pending further talks aimed at resolving the dispute.