Joey Barton
Arsenal are interested in midfielder Joey Barton after he was handed a free transfer by Newcastle yesterday. REUTERS

Arsenal's hopes of signing Juan Mata diminished last night after the deadline passed for the Valencia forward's £18m buyout clause. The Spanish side are reluctant to sell the 23-year-old and can now refuse to sell to any club who fail to meet their own buyout clause, believed to be around £52m.

Tottenham tried to activate the clause on Saturday but Mata indicated he did not want to move to White Hart Lane because he wants to play Champions League football.

Arsenal have been monitoring Mata throughout the summer but any deal for an additional attacker is contingent on the outcome of Cesc Fabregas's protracted transfer to Barcelona.

Barcelona remain cautiously optimistic of signing Fabregas, despite Arsenal rejecting a £27m bid earlier this summer. Reports suggest the European champions are ready to table another offer worth as much as £35m for the Spain international.

Part of that money is likely to fund a move for Mata with Arsenal confident the Spaniard will still be available for £18m.

A central defender remains Wenger's priority - with Everton's Phil Jagielka the primary target - but the Frenchman has been alerted to the availability of Newcastle midfielder Joey Barton, who was yesterday handed a free transfer by the Magpies.

Newcastle are reported to have grown tired of the volatile midfielder's attitude - particularly on Twitter - and will allow the 28-year-old to leave on a free this summer.

"Newcastle United can confirm that Joey Barton has been placed on the transfer list today [Monday]," a club statement read.

"The player has been advised he can leave the club on a free transfer."

Barton responded to the club's statement on Twitter, saying: "Somewhere in those high echelons of NUFC, they have decided, I am persona non grata.

"I am on a free but the honour of wearing those B+W stripes, surpasses that.

"One day the board might realise, what the shirt signifies. HONOUR and PRIDE. Thanks for your continued support......#toonarmy."

Meanwhile, Wenger has been handed another headache ahead of his side's opening game against Newcastle on 13 August, after reports suggested Manchester City are ready to make a £22m bid for Samir Nasri in the next 48 hours.

An unnamed source at the Sun says City will submit a "take it or leave it" offer for Arsenal's French midfielder before the end of the week.