"The Board would like to place on record their sincere thanks for his service and contribution. The club will be making no further comment at this time."

Birmingham issued a statement on Saturday in response to banners that had been put up by a Blues fans' protest group in Blackburn town centre before their final game of the season at Ewood Park.

City claimed one of the banners was "undoubtedly racist" and that it was "unacceptable".

Birmingham finished 18th in the Sky Bet Championship and Ren has come under increasing pressure from supporters to step down.

Fans demonstrated against owners TTA and Ren, known informally as Dong, in particular before City's 3-0 home defeat to Bristol City in March and there have been further protests.

Aitor Karanka stepped down from his role as head coach in March after signing a three-year deal in the summer to replace Pep Clotet.

Former Charlton boss Lee Bowyer was announced as Karanka's successor soon after and steered City clear of relegation as they finished nine points above the bottom three after losing their last two matches.