Arsenal are set to step up their attempts to bring in a defender before Thursday’s transfer deadline after agreeing a £4.6million deal to sell Laurent Koscielny to Bordeaux.

The 33-year-old is desperate to return to France after refusing to travel on the club’s pre-season tour to the United States and rejecting several attempts from head coach Unai Emery to persuade him to see out the final year of his existing contract.

Koscielny demanded to be released from that obligation altogether and granted a free transfer but Arsenal in recognition of his nine-year service to Arsenal. The club dismissed that suggestion but reluctantly allowed him to leave only if they received a fee.

The centre-back will undergo a medical on Tuesday having already agreed personal terms with Bordeaux.

Emery had hoped to convince Koscielny to stay on given they must wait until next summer to include William Saliba in the first-team squad. Saliba is a £27m summer signing from Saint-Etienne but he has been loaned back to the French club for the 2019-20 campaign.

There was genuine surprise Koscielny had agitated so decisively for a move but Emery believed his captain's previous record of professionalism would have made his reintegration a realistic proposition.

However, Koscielny made it clear he would not play for the club again and so Arsenal agreed a deal in the hope they can sign a replacement in the next 48 hours.

The Gunners are keen on Red Bull Leipzig defender Dayot Upamecano but have been quoted a price of around £70m with the German side basing their valuation on similar transfer fees agreed for Virgil van Dijk and Harry Maguire.

Having already agreed a £72m deal for Nicolas Pepe, money is in short supply at Arsenal. That transfer was only agreed because Lille accepted the money staggered over five years.

The Gunners will seek to make similar arrangements with Leipzig in pursuit of a deal for the 20-year-old but they are reluctant sellers with Julian Nagelsmann viewing the Frenchman as a key part of his plans this season. Juventus centre-back Daniele Rugani is another alternative but his £50m price tag looks equally prohibitive.

Arsenal remain hopeful of agreeing a deal for Celtic left-back Kieran Tierney – who Emery also views as a possible centre-back option – but had a £25m offer rejected last month.

Meanwhile, Nottingham Forest are in talks to sign Carl Jenkinson. The right-back is surplus to requirements and is available for around £5m.