BUENOS AIRES (Reuters) - Spain's Repsol SA filed a complaint against Argentina before the International Center for Settlement of Investment Disputes (ICSID) on Monday over its nationalization of energy company YPF SA , a source familiar with the matter told Reuters.

In May the government of Argentina seized 51 percent of the country's biggest oil company from Repsol, accusing the former parent company of underproduction and under-investment.

(Reporting By Alejandro Lifschitz, writing by Hugh Bronstein; Editing by Gerald E. McCormick)