The 29-year-old Argentine - who played under Rafa Benítez at Napoli - has won 32 full caps for his country and has put pen to paper on an initial two-year contract after the Magpies agreed an undisclosed fee with the Swans.

He began his career in his homeland with Estudiantes before moving to Napoli in 2011.

He won the Copa Italia with Gli Azzurri in 2014 as well as playing in the Champions League.

Fernández signed for Swansea in the summer of 2014 and made more than 100 Premier League appearances for the Welsh club.

Speaking about his arrival on Tyneside, Fernández said: "It was a long day but I’m really happy to be here.

"It’s a new challenge in my life and I’m very excited to meet all the players and staff here."

Manager Benítez added: "I know Federico well from our time together at Napoli and it was an easy decision to bring him here.

"He is experienced, a very good professional and he will add competition in defence."

The player will wear the number 18 shirt for Newcastle United and will be eligible to face Tottenham Hotspur on Saturday.