Celtic have told Arsenal they must go higher to sign Kieran Tierney.

The Mirror says Arsenal's improved £25million offer for Celtic left-back Tierney has been rejected, according to reports.

The Gunners were reported to have made an improved bid for the Scotland defender on Friday , after their initial £15million bid was turned down last month.

Celtic had been holding out for £25million, and while Arsenal's improved offer is believed to reach that sum when including appearance-based add-ons, it doesn't give the Scottish Premier League champions the figure up front.

Gunners boss Unai Emery has just £45million to work with this summer after they failed to qualify for next season's Champions League.