Unai Emery expects more players to follow Laurent Koscielny and Alex Iwobi out of the Arsenal exit before the European transfer windows close.

Arsenal had a busy close season before the English transfer window finished on Thursday, strengthening with the arrivals of Nicolas Pepe, Dani Ceballos, Gabriel Martinelli, Kieran Tierney and David Luiz, the latter two signing on deadline day.

Many more players left the club, however, with Petr Cech retiring, Danny Welbeck, Stephan Lichtsteiner and Aaron Ramsey departing on free transfers, and Carl Jenkinson, Koscielny and Iwobi sealing moves.

Former captain Koscielny left on sour terms after refusing to go on their pre-season tour, while Iwobi went to Everton in a deal reportedly worth up to £40million.

Mohamed Elneny and the much-maligned Shkodran Mustafi have reportedly been made available for transfers, and while Emery did not mention any names, he does expect more players to leave for overseas clubs.

"We were changing players at the last moment," he said of Arsenal's deadline day deals.

"We had with Laurent Koscielny the first captain, but just five days ago he left. Other players came in, we finished our market, but it is at the moment open in other countries.

"In the next 20-25 days some players will leave. It's the reason, I want to close [complete] our squad, clearly."

The signing of David Luiz from Premier League rivals Chelsea came as a surprise to many, but after the experienced Koscielny departed, Emery is adamant the Brazilian is an important addition.

"We worked together for two months at PSG," Emery said of David Luiz. "After three matches [at PSG], the club and he decided to sign for Chelsea.

"He's a big opportunity for us, he decided to join Arsenal. He wants to do something important with us.

"He has experience, quality in build-up, he is a good defender and he is coming here to help us with his capacity and quality."