Wenger shores up defence with £10m Vermaelen

Arsene Wenger's pressing need for central defensive reinforcements saw him complete Arsenal's first big summer buy yesterday as the Belgium international defender Thomas Vermaelen joined from Ajax for £10m.

In a move which will encourage Manchester City to bid £12m for Kolo Touré, Vermaelen completed a medical at London Colney yesterday morning which set the seal on a four-year deal worth £50,000 a week. The 23-year-old, a regular in the Belgium side with three years' international experience, can play either at left-back or centre-back but it is the latter where he appears to be most needed, despite Milan's decision not to take up a £6.3m option to convert Philippe Senderos's loan into a permanent move.

Vermaelen's arrival at the Emirates will lift City hopes that they might be able to entice Touré to Eastlands. The Arsenal defender was one of their top targets in January but, after initially appearing keen to move north, cooled on the idea.

The former Arsenal captain Tony Adams has raised doubts about Vermaelen's height – he is 5ft 11in – but Robin van Persie is among those who have vouched for the qualities of a player who would leave Wenger less vulnerable for cover if one or both of Touré and William Gallas depart. Gallas has been persistently linked with a move to Juventus and Milan.

Vermaelen joined Ajax in 2003 from Belgian side Germinal Beerschot and has made over 100 appearances for the Dutch club. "Arsenal is a great club with a world-class manager, high quality players and a fantastic stadium," he said yesterday. "I joined this club because I know Arsenal will be challenging for trophies."

Vermaelen explained that Wenger had quickly convinced him of his value to Arsenal. "It was a very short call but I felt the respect," he said. The Gunners hope his arrival will prove their ambition to Van Persie and convince the Dutch striker to sign his new £90,000-a-week deal. "He is a solid performer with good experience of Champions League and Uefa Cup football," Wenger said of his new signing.

Wenger admitted last month that his side must shore up their defence. "In the passing quality in the final third and in the opposition half, we are as good as Manchester United," he said. "We have conceded more goals and that is where the difference lies; we have conceded 36, they have conceded 24."

*Chelsea have told Uefa that they will appeal the £85,000 fine and six-game ban handed out to Didier Drogba and Jose Bosingwa's four-game ban imposed in the wake of the Champions League semi-final against Barcelona.