MADRID - Telefonica told unions on Monday it sought to cut around 5,100 jobs in Spain by 2026 in an effort to reduce costs and adapt the company's size to the current market, a UGT union spokesman said.

Spain's largest telecom company employs about 21,000 people in its home country, while its global workforce is over 103,000.

The company based the decision on productivity, organization and technical reasons, the union spokesman said as Telefonica and the unions started negotiating the layoffs.

Telefonica confirmed the labour "adjustment" in a statement but declined to say how many jobs it intended to axe.

(Reporting by Inti Landauro and Matteo Allievi, editing by Andrei Khalip)