Arsenal target Laurent Koscielny

Arsenal have agreed a deal to sign 24-year-old centre half Laurent Koscielny from Lorient for an initial £8.1million.

Heart of the defensive matter: Lorient defender Laurent Koscielny will join Arsenal in a £10m deal The French defender will sign a four-year deal at the Emirates Stadium and add-ons could see the fee could rise to £10m.

The Gunners interest in Koscielny was first revealed last month, but negotiations have not been easy with the Ligue 1 club.

The Gunners have agreed to let promising 19-year-old midfielder Francis Coquelin join the club on a year-long loan to ease things through quickly.

The deal is expected to be announced before the weekend and provides Arsene Wenger with much-needed back-up in a problem position.

Veterans Mikael Silvestre, Sol Campbell and contract rebel William Gallas could all leave this summer. This will leave just Thomas Vermaelen and Johan Djourou as specialist centre backs with Djourou having made just one appearance all last season and only 48 in the League since 2004.

Koscielny was little-known a year ago when Lorient signed him from Ligue 2 side Tours for just £1.5m but an impressive season brought him to the attention of Wenger.

Koscielny is yet to be capped by France and could pledge his international career to Poland thanks to familial roots.