Arsenal are open to letting Laurent Koscielny leave the club provided their valuation is met, Sky Sports News understands.

The Gunners have opened internal disciplinary proceedings against Koscielny after he refused to travel on a pre-season tour to the United States.

Koscielny has one year remaining on his contract and wants to be released for free and be able to return to France.

Speaking after Arsenal's 3-0 win over Colorado Rapids, Unai Emery said: "For me as a coach Koscielny's an important player. Now it's a matter for him and the club".

3:41 The Transfer Talk panel discuss the potential repercussions from Laurent Koscielny's refusal to travel with Arsenal on their pre-season tour to the USA The Transfer Talk panel discuss the potential repercussions from Laurent Koscielny's refusal to travel with Arsenal on their pre-season tour to the USA

Meanwhile, Arsenal's latest bid for Celtic left-back Kieran Tierney has been rejected, Sky Sports News understands.

Arsenal's offer was worth in the region of £25m but it is understood Celtic were unhappy with the structure of the bid and want more cash upfront rather than in add-ons.

3:44 The Good Morning Transfers team discuss what Kieran Tierney would bring to Arsenal, how his addition might affect the line-up, and how he compares to Andy Robertson The Good Morning Transfers team discuss what Kieran Tierney would bring to Arsenal, how his addition might affect the line-up, and how he compares to Andy Robertson

Arsenal are close to agreeing a deal with Saint Etienne for William Saliba which would see the defender return to the French club on loan.

Tottenham are also close to a deal for the 18-year-old and it is likely the player will decide where he goes.

Reports in France suggest Saint Etienne are relaxed about the situation and are angling to get even more money out of the two north London clubs.