Top scorer in La Liga this season with 11 goals in 10 appearances, Costa told Spain coach Vicente del Bosque this month that he was available for the world and European champions.
Del Bosque's Brazil counterpart Luiz Felipe Scolari responded last week by announcing he planned to call Costa up for next month's friendlies against Honduras and Chile.
"The player communicates in the letter addressed to Julio Cesar Avellada, secretary general of the Brazilian soccer federation (CBF), his wish to be available to the Spanish national team," the Spanish soccer federation (RFEF) said on its website (www.sefutbol.com) on Tuesday.
"Diego Costa will be able to play for Spain ... if the coach deems it opportune."
Costa's first chance to feature for Spain could come on Nov. 19 when they play South Africa in a friendly at Soccer City in Johannesburg, scene of their maiden World Cup triumph in 2010.
He represented Brazil in friendlies against Russia and Italy in March but was left out of the squad for June's Confederations Cup and is not tied to one country until he has played in an official game.
Tall and powerful in the air, Costa has an excellent touch and vision and is always a handful for opposition defences who find it tough to cope with his physical approach that sometimes pushes the boundaries of fair play.
His first clubs in Europe were in Portugal and he moved to Atletico from Braga in 2007 before passing through Celta Vigo, Albacete, Real Valladolid and Rayo Vallecano, the club where he scored 10 goals in 16 La Liga appearances in 2011-12.
Last season Costa was instrumental in Atletico's triumphant King's Cup campaign, scoring his eighth goal in eight appearances in the 2-1 win over Real Madrid in the final.
He will face stiff competition for a place in Del Bosque's squad for next year's World Cup in Brazil from the likes of Alvaro Negredo, Fernando Torres, David Villa, Roberto Soldado and Fernando Llorente.
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