Wenger fights to keep £6m Senderos: Can Arsenal boss win his latest battle?

have made a shock bid for Arsenal defender Philippe Senderos, increasing the growing tension between Arsene Wenger and his board over the continuing exodus of players.

The Arsenal manager was stunned when the offer of about £4million arrived on Wednesday and even more bemused when it was not rejected out of hand by the club.

Arsenal's board will hold out for about £6m, but their willingness to consider allowing another first-team squad member to leave after four high-profile departures this summer will alarm supporters and Wenger.

Fans are already concerned that the loss of Alexander Hleb, Mathieu Flamini, Gilberto Silva and Jens Lehmann has damaged a squad that is weaker than the one whose Premier League title challenge collapsed under the weight of injuries and inexperience.

With the future of top scorer Emmanuel Adebayor also uncertain, the signings of teenage sensation Aaron Ramsey and France midfielder Samir Nasri have not been enough to quell a sense of growing unease.

Senderos is far from a supporters' favourite, having made costly mistakes in high-profile games, and Wenger agrees with his board that the Swiss stopper struggles at the highest level.

But while the manager wants to keep the player, his directors believe selling at the right price would represent good business.

The only significant obstacle to a deal appears to be concern over Kolo Toure's bout of malaria. It is thought Toure will recover to start the new season, but if that assessment changes, Senderos will be required to stay, especially since another cover player, Alexandre Song, will be playing for Cameroon at the Olympics.

The Arsenal board's response to Newcastle's bid gives further weight to rumours of financial problems at The Emirates, which were fuelled by the sudden sacking of chief executive Keith Edelman in May.

The search for Edelman's replacement continues and further off-field instability, including the stand-off over Uzbek billionaire Alisher Usmanov's desire to buy Arsenal, has not made life easy for Wenger.

When former vice chairman David Dein was forced out more than a year ago because of his support for a takeover - he is now chairman of Usmanov's Red and White Holdings, the largest single shareholder in Arsenal - Wenger lost a trusted friend and ally who handled every aspect of transfers at the club.

Senderos, though, would be a welcome addition to Kevin Keegan's squad as the Newcastle boss revamps a defence who conceded too many sloppy goals last season, and who lost 1-0 at Championship side Doncaster yesterday.

'I'm expecting one or two new faces to come in,' said Keegan, who is pursuing Blackburn left-back Stephen Warnock, despite having a £3.75m bid rejected. 'We only have one right-back and one leftback. We do need one or two additions and things will start to happen in the next week to 10 days.'