MADRID, Aug 30 (Reuters) - Barcelona announced on Tuesday the signing of Spain forward Paco Alcacer from Valencia on a five-year contract.

He moves to the Nou Camp on his 23rd birthday for a fee of 30 million euros ($33.5 million) and is likely to be the Spanish champions' last signing in the transfer window.

Alcacer's buyout clause has been set at 100 million euros and the player, who is on international duty with Spain, will be unveiled next week.

Barca's priority was to add a striker but they lost out on signing Nolito and Kevin Gameiro, with the former joining Manchester City and the latter Atletico Madrid.

Alcacer is Barca's fourth attacking option behind Lionel Messi, Luis Suarez and Neymar.

He scored 13 times last season in La Liga.

Alcacer had been at Valencia since 2005 and has featured at every age-group level for Spain.

The Torrente-born player is the Catalan side's sixth singing of the summer following the arrivals of Jasper Cillessen, Denis Suarez, Lucas Digne, Samuel Umtiti and Andre Gomes.

($1 = 0.8955 euros)

(Reporting by Adriana Garcia, editing by Ed Osmond) ((Cindy.Garcia@thomsonreuters.com;))