Black football managers are given less time than white counterparts to turn poor form around, claims John Barnes.
The former Celtic, Jamaica and Tranmere boss told BBC Scotland he believes unconscious bias is commonplace.
The 56-year-old said: "Results get you sacked. For the vast majority of black managers, they will be sacked quicker than a failed white manager.
"There is no evidence. It's just a feeling that we get and the statistics will suggest that."
Barnes, born in Jamaica, starred for Watford, Liverpool and England in the 1980s and '90s. He was appointed head coach at Celtic in 1999, with fellow Liverpool favourite Kenny Dalglish installed at the same time as director of football.
However, Barnes' time at the Glasgow club was fraught and he was sacked following the 3-1 Scottish Cup defeat by second-tier Inverness Caledonian Thistle. His team had won 13 and drawn two of their 20 league games.
In the past week he has expressed his views on Twitter and responded to comments made by fans about the restricted opportunities for black managers and how quickly they may be sacked relative to their white counterparts.
"I was just engaging with people," he explained. "It went on to become personal, or all about Celtic and all about racism in football, but that was not what it was all about.
"How can you prove it? You can't. Even with statistics, it could still be coincidence.
"There's not one British black manager who has been at a club more than one or two years, which would suggest if it wasn't anything to do with bias whatsoever, all black managers are not good enough, because they're black."