Atletico tie Brazilian striker Costa until 2018

MADRID (Reuters) - Atletico Madrid have agreed a three-year contract extension with Brazilian striker Diego Costa which secures his services in the Spanish capital until 2018, the La Liga club said on Wednesday.

Atletico Madrid's Costa reacts during the Spanish first division soccer match against Valencia at Vicente Calderon stadium in Madrid

The 24-year-old scored 20 goals in all competitions last season, and was top scorer in the King's Cup with eight, as the side went on to lift the trophy beating Real Madrid 2-1 in the final.

"Costa is one of the key pieces in the team and it continues our policy of trying to maintain the group that have brought us so much success in recent years," Atletico sports director Jose Luis Caminero told the club website.

"Extending his contract was one of our objectives."

Atletico, who finished third in La Liga last season to qualify for the Champions League group stages, open their league campaign away to Sevilla on Sunday.

(Reporting by Mark Elkington; Editing by John O'Brien)