• Barcelona yet to table an official bid for the Arsenal captain • Phil Jagielka seen as answer to club's defensive problems

Cesc Fábregas will be allowed to leave Arsenal this summer but only if Arsène Wenger convinces Samir Nasri to stay at the club, with the manager more inclined to listen to offers for his captain should the French midfielder sign a new deal.

Wenger has identified Everton's Phil Jagielka, and not Bolton Wanderers' Gary Cahill or Christopher Samba of Blackburn Rovers, as the prime candidate to solve his perennial problems in central defence. It is thought that Wenger tried to sign Jagielka in the previous transfer window in January.

He is also keen on the midfielder Ricardo Alvarez, who plays for Vélez Sársfield in Argentina. Palermo are interested in the 23-year-old and, although their president, Maurizio Zamparini, may have been premature in saying on Friday that "Alvarez has given us the slip and signed for Arsenal", it appears a deal may be close.

There has still been no recent official bid for Fábregas, with the hierarchy at the Emirates aware of an offer of £27m from Barcelona that is long-standing.

Although the Catalan club are expected to step up their interest in Fábregas this summer, Wenger's priority is to tie the 23-year-old midfielder Nasri to a fresh contract as he has only a year left on his agreement, whereas Fábregas's runs until 2015. The manager is assessing the priorities for his squad before a crucial season for Arsenal, and his own career, as he seeks to end what would be a seven-year trophy drought by the close of the campaign.

He is conscious that Fábregas, who is on holiday in Bali before he returns to his family home in Barcelona next week, does not fit easily into a 4-4-2 and the manager is deciding how best to perform surgery on the structure and personnel of his squad. Wenger is aware that Fábregas, whom he signed from Barcelona as a 16-year-old in 2003, is firmer than ever in his intent to depart for his home club even though he has not lodged an official transfer request.

After Nasri's stand-out season in the last campaign, which tailed off only towards the close following the fall-out from the disappointment of losing the Carling Cup final to Birmingham City, Wenger is willing to offer him improved terms that will raise his salary to £100,000 a week as he attempts to stave off interest from Manchester United, who head a queue of suitors.

Regarding the prospect of a move to Old Trafford Nasri, who turns 24 on Sunday, said this month: "I don't know if I will sign a new contract. Anyway, the discussions are ongoing."

Although Wenger is not looking to move Fábregas on, he is also not entirely opposed to the midfielder leaving, yet he knows that this should not happen before Nasri's future is determined because of the negative signals this would offer to Arsenal's rivals and supporters.

If Nasri does depart, then Wenger will be all the keener to hold on to Fábregas. But if he can convince Nasri to stay, then the healthy professional relationship between Ivan Gazidis, the Arsenal chief executive, and Sandro Rosell, the Barcelona president, may come into play.

Both serve on Fifa, Uefa and European Clubs Association committees and occasionally take lunch together where conversation can turn to Fábregas's future.

Peter Hill-Wood, the Arsenal chairman, confirmed last week that the Champions League winners have recently restated their interest in the midfielder.

"Yes, they have spoken to us about Cesc. They have been in touch. But so far they have not made a bid and we do not want to let him go," he said. "But he comes from Barcelona, so it is understandable if he wanted to go back. However, they have not made an offer so far."

Wenger is continuing discussions with Lille to try to sign Gervinho, the Ivory Coast striker who scored 15 goals as the French club won their domestic league and cup double. If he does join the club, the 24-year-old, who played in last summer's World Cup, is likely to cost around £12m.

Cahill and Samba remain on Wenger's radar and so does the Belgian winger Eden Hazard, Gervinho's 20-year-old team-mate, but Nicklas Bendtner, Tomas Rosicky, Denílson and Carlos Vela are free to leave the club as part of a major rebuilding drive.