SAO PAULO, June 21 (Reuters) - Brazilian lender Itau Unibanco reached a deal to acquire a minority stake in a power plant complex owned by energy company Eneva's for 1 billion reais ($210 million), Eneva announced in a securities filing on Wednesday.

Under the deal, Itau will hold 15.02% of the total capital stock of Eneva Participacoes III, an Eneva subsidiary that owns six power plants in the Parnaiba Complex in northeastern Brazil. ($1 = 4.7630 reais) (Reporting by Peter Frontini and Carolina Pulice; Editing by David Alire Garcia)