Arsène Wenger has categorically ruled out the prospect of Samir Nasri leaving this summer, going so far as to suggest that Arsenal could not be considered a "big club" if they lost both the France midfielder and Cesc Fábregas.

Wenger has chosen to hold on to Nasri even though it could cost the club upwards of £20m in lost transfer fees, and the manager said he would "fight until the last second" to keep Fábregas, despite admitting his captain was "torn" over his desire to rejoin Barcelona.

Nasri, a target for both of the Manchester clubs, who are prepared to start the bidding for him at £20m, has entered the final 12 months of his contract in north London and he has so far ignored Arsenal's offer of fresh terms, believed to be worth £90,000 a week.

But Wenger, speaking at the club's pre-season tour base in Malaysia, said that he would rather have Nasri for one more season and lose him as a Bosman free agent than sell him now. There remains the hope at the club that Nasri could yet re-sign and the prospect might be helped if Fàbregas were to secure his move to Barcelona. Nasri would then enjoy a more central role in the midfield.

As Wenger confirmed the £10.6m signing of the Ivory Coast and Lille forward Gervinho, Fábregas's future was less clear. Wenger continues to battle to convince the Spaniard that he ought to remain at the club which has nurtured him since 2003 but he conceded that he could leave.

The saga looks set to run, with Barcelona, despite having indicated that they would pay £35m for him, content to bide their time. Wenger wants Fábregas to commit quickly so that he can accelerate his team-building plans but he made it plain that Nasri was staying.

"Samir's situation is clear for me," Wenger said. "He stays. We are in a [financial] position where we can say 'No' and we will, in the case of Samir." Wenger said that it was better to keep Nasri for another season and risk losing him for nothing than to sell him to United or City before the closure of the transfer window, even if it represented a £20m gamble.

"You are the same people who reproach me for not spending money and now you reproach me for wanting to spend it," he added, with a smile. "It is in the interests of the club. Fábregas is in no-man's land ... Imagine the worst situation, that we lose Fábregas and Nasri; you cannot convince people that you are ambitious after that."

Wenger was asked what would happen if Fàbregas said he was unhappy. "That's the only way he could get out," he replied. "I don't think he's unhappy but he wants to go back to Barcelona. For us, it's not a question of money. It's a question of Cesc wanting to be with us. And I think he is torn because he loves the club deeply."

Robin van Persie is desperate for Fábregas and Nasri to stay – he said that the former "would be a miss for any team" – and he stressed the need for Wenger to add quality to the squad. It is not inconceivable that Van Persie, who is under contract until 2013, would consider his future if he were unimpressed by the club's transfer business.

"The way I feel now is that a few signings are more than welcome," he said. "Every other team is buying quality players so hopefully we will do the same. You need investment to keep up. Everyone needs competition because no one really wants to go to sleep. In an ideal world, no one should be really sure of his place, except maybe the captain and the goalkeeper.

"Why not sign a player for £20m-£25m? These days, proper players cost money. Sometimes, it can be a statement for the others as well. But the main thing is it's not just a label, a multimillion-pound signing. It's more about the quality."