The 19-year-old striker says he is “making history because no other Costa Rican player has ever played in a team with the quality of Arsenal.”

Campbell represented Costa Rica at the recent Copa America and the Under-20 World Cup.

Arsenal manager Arsene Wenger said: “We took a gamble on him but, from what we have seen, it is worth taking.”

The striker is Arsenal’s fourth signing since the end of last season, following Carl Jenkinson, Gervinho and Alex Chamberlain into the Emirates Stadium.

Contract details were not released.