Birmingham City co-owner David Sullivan has heavily criticised striker Dwight Yorke's performances for Blues as "disrespectful" to supporters.

The Blues boss openly questioned Yorke's work-rate and said he was "not the most successful signing" the club had made.

Sullivan, who made his remarks to The Birmingham Post in an interview at the Essex mansion where he conducts his business affairs, was speaking as the future of Yorke at Blues looks uncertain.

The striker yesterday returned from a trip to Australia and the United Arab Emirates in which he had hoped to find a new club.

Sullivan said Yorke's workrate at Blues' game at Blackburn Rovers in December - where the striker was racially abused by a small section of the crowd - was below the standard expected by the club's supporters.

He compared that performance to Walter Pandiani's and Mehdi Nafti's efforts for Blues in their 1-1 draw at league leaders Chelsea last Saturday.

The two on-loan players have recently broken into the Blues first team following moves from Deportivo La Coruna and Racing Santander.

Sullivan said: "Dwight Yorke is being paid #20,000 a week by Birmingham City and has not been one of our most successful signings.

"He is a straggler, which is not enthralling for the fans. He does not appear to be very energetic which is disrespectful to Birmingham City fans.

"He appeared to not even break into sweat against Blackburn.

" In our performance against Chelsea last week Nafti ran his socks off, Pandiani ran his socks off. That is what people want to see at Birmingham City - total effort."

Blues manager Steve Bruce said in January that Yorke would be leaving the club, claiming it would be best "for all concerned" if the Trinidad and Tobago striker moved.

Yorke, who signed for Blues on a years' contract hours before the transfer window closed last August, has not played for the club since the 2-0 loss to Chelsea at St Andrew's on January 30.

Sullivan also revealed there is a clause in Yorke's contract which stipulates that Blues have to give the player another year's contract if he plays more than 60 per cent of Birmingham's fixtures this season.

Yorke, who is only two games away from reaching that quota, has been urged to sign a 'waiver' so that he could play more games without Blues having to commit itself for another year, Sullivan said.

He said the club wants Yorke to be "put in the shop window" so that he can be inspired to provoke interest from other clubs.

However, Yorke has refused to sign the waiver, which leaves Birmingham with no option but to leave him out of the squad except in "emergency circumstances", the co-owner added.

In a further effort to offload the striker, Blues have offered to make up the difference to Yorke for the cut in wages he is expected to be given at his next club. This would ease the financial burden on Yorke's future club, and would also cut Blues current #20,000 a week outlay.

Yorke has slipped further down the pecking order at St Andrew's following the arrival of Uruguayan forward Pandiani, who has formed a formidable strike partnership with Emile Heskey.

Irish international Clinton Morrison and Robbie Blake, who Blues signed from Burnley for #1.25 million in January, are also more likely to be included in the starting line-up.

Sullivan was embroiled in a race row following Blues visit to Blackburn last year after he suggested Yorke 'overreacted' when he was subjected to monkey taunts.

Four men were convicted of racially taunting the striker during the game.