Arsenal has signed Mathieu Debuchy and selling club Newcastle has replaced the defender with Daryl Janmaat.

The 28-year-old Debuchy, who was part of France's World Cup squad, joined Arsenal for 12 million pounds ($20.5 million), becoming the London club's second summer transfer window signing after forward Alexis Sanchez.

Newcastle reinvested around half of the Debuchy fee to replace the right back with 24-year-old Janmaat from Feyenoord.

Swansea also announced on Thursday that striker Michu joined Napoli on a season-long loan deal, with the Italian club holding an option to make the transfer permanent.

The 28-year-old Spaniard arrived in south Wales two years ago, scoring 22 goals during his first season at Swansea, but struggling to recapture that form last term as injuries took a toll.

West Ham signed Ecuador striker Enner Valencia on a five-year contract from Mexican club Pachuca, a deal which is dependent on him receiving a work permit.