Former Sunderland striker Kevin Phillips believes Darren Bent's demand for a move away from the Stadium of Light is motivated by "pure money".Phillips, 37, who now plays for Birmingham, spent six years on Wearside from 1997 to 2003. [LNB]"I'm very surprised. If you are asking me, I think it just boils down to pure money," Phillips told BBC Radio 5 live. [LNB]Bent's transfer request was confirmed by Sunderland on Monday, with Aston Villa reportedly keen to sign him. [LNB]With the transfer window only open for another two weeks, Villa are believed to have backed under-pressure manager Gerard Houllier with an £18m offer for the 26-year-old England forward. [LNB] There's still some twists ahead I reckon Mr-SAFC aka MensahsFitnessCoach Bent has been a key figure in Sunderland's climb to sixth in the Premier League table, scoring eight of their 24 goals this season. [LNB]However, he has only found the net twice in his last nine appearances and Phillips believes he could face criticism from fans if they conclude his recent dry run is connected to his desire for a move. [LNB]"I speak to people who go to games week in week out and he hasn't performed in the last three or four games," said Phillips. [LNB]"They have been a little bit disappointed with him and now this is coming out they are probably putting two and two together. [LNB]"I feel sorry for (manager) Steve Bruce. They are putting together a fantastic squad and want to keep their best players." [LNB]Bent began his career at Ipswich but left for Charlton in 2005 in a £3m deal after refusing to sign a new contract at Portman Road. [LNB]After scoring 31 goals in 68 league appearances for an Addicks side relegated from the Premier League in his final season, Bent moved to Tottenham for £16.5m in June 2007 after turning down a switch to West Ham. [LNB]His departure from White Hart Lane to Sunderland for £10m in August 2009 was also less than straightforward. [LNB]The move was concluded after Bent criticised Spurs chairman Daniel Levy for pursuing negotiations with Hull and Stoke, although the striker subsequently apologised for his Twitter comments.