FILE PHOTO: The logo of Telefonica is seen on company's headquarters in Bogota, Colombia May 28, 2019. REUTERS/Luisa Gonzalez

MADRID (Reuters) - Telefonica plans to offer voluntary redundancy to up to a fifth of its workforce in Spain, a person with knowledge of the matter said on Monday, as the telecoms company struggles to boost earnings in its home market.

Europe’s third-biggest telecom company will make the offer to all employees over 53 years of age, who total just under 5,000 in a national workforce of 25,000, at a meeting with labor unions on Sept. 11, the person said.

A Telefonica spokeswoman declined to comment.

Large telecom firms across Europe have been struggling to post strong growth against fierce competition. In ever-more crowded Spain, London-listed Vodafone VOD.L said earlier this year it planned to cut up to 1,200 jobs.

Telefonica’s multibillion euro investment in deploying Europe’s biggest fiber network in Spain is key to its reaching 2019 targets for 2% revenue growth and a 2-percentage point rise in margins.

Its shares have fallen more than 10% so far this year, a challenging market backdrop which partly motivated a decision to bring forward its regular board meeting to Sept. 10.