Iberia is looking to cut another 1,581 jobs—on top of the 3,100 redundancies it is already rolling out—under a consultation that was formally launched Friday.

The staff consultation, which was announced to the London Stock Exchange by Iberia parent International Airlines Group (IAG), will run for a maximum of 30 days and will establish the exact numbers, functions and timings of the redundancies.

“Iberia has today informed its employees and trade unions that it intends to start a consultation period for a collective redundancy process which will involve up to 1,581 jobs. This option was discussed as part of the collective bargaining negotiations with the airline’s unions last April. It is a continuation of Iberia’s transformation plan to introduce permanent structural changes across the airline enabling it to grow profitably in the future,” IAG said in the brief stock market disclosure.

An IAG spokeswoman told ATW the job cuts will be voluntary, building on pay and productivity agreements, which were agreed with unions earlier this year. She added that the potential for further cuts was revealed at the release of IAG’s financial results in February, but this marks the start of the formal staff consultation process.

This latest downsizing comes in addition to the 3,100 job cuts, which were agreed through mediation and will be completed by early 2015, affecting a range of functions across the airline. The majority of these cuts are also voluntary.

As of Dec. 31 2013, Iberia had approximately 18,000 employees.