Merino, who is on loan at St. James’ Park from German side Borussia Dortmund, has been called up by Albert Celades for their double-header next month.
They face Italy in a Under-21 European Championship qualifier on Friday, 1st September before taking on Estonia in the same competition on Tuesday, 5th September in Tallinn.
Merino has made two appearances for Newcastle so far this season, appearing as a substitute against Tottenham Hotspur before starting at Huddersfield last weekend.