Unions representing employees of Spanish airline Iberia said Thursday they will go on strike for six days prior to the Christmas holidays.

The work stoppage has been planned for Dec. 14 and Dec. 17-21 to protest a restructuring plan that includes the layoff of 4,500 of the struggling carrier's 20,000 employees.

The strike affects "all of the company's work centers and activities," including flight operations, the federal secretary of the UGT labor federation's airline division, Francisco Rodriguez, said in a press conference.

He said that while the SEPLA pilots' union did not join in the formal strike call, the pilots agree that the restructuring announced earlier this month by the airline's parent company - the International Airlines Group - is not "a viability plan, but rather a plan to dismantle" Iberia.

Rodriguez had previously said the restructuring plan would dismantle the company and slammed it for placing exclusive blame for "management's failure" on the workers.

The restructuring plan for Iberia, which posted a record operating loss of 262 million euros ($340 million) for the first nine months of 2012, is aimed at restoring profitability, IAG, formed in 2011 by the merger of Iberia and British Airways, said in a Nov. 9 filing with Spain's CNMV stock market regulator.

The announcement of Iberia's restructuring, which also will involve eliminating 25 airplanes - mostly short-haul aircraft - and reducing operating capacity by 15 percent in 2013, coincided with the release of IAG's third-quarter results.

The holding company lost 39 million euros ($50.6 million) in the first nine months of the year - due in large part to troubles at Iberia - after posting a 338 million euro profit for the same period of 2011.

IAG said then that a Jan. 31, 2013, deadline has been set for reaching a deal with the unions, but that if no agreement is signed more job cuts and a greater reduction in Iberia's size and operations will be necessary to safeguard the company's future.

Iberia CEO Rafael Sanchez-Lozano acknowledged earlier this month that the plan is harsh but that if profound structural changes are not put in place the "company's future is bleak."

He said then that Iberia was losing money at the tune of 1.7 million euros ($2.2 million) per day across all of its markets, adding that although the sovereign debt crisis battering Spain has affected Iberia, the airline's problems are structural and predate the country's current economic woes.

In statements prior to Thursday's official strike announcement, Sanchez-Lozano told Radio Cope that the planned job action is "absolutely inappropriate and irresponsible."

The executive added that it is also "unjustified" because the company is willing to "discuss alternatives." EFE