However, a visa issue may hamper Rovers’ attempts to sign the South Africa international defender.
Khumalo, a free agent following his release from Tottenham, suffered a serious knee injury playing for his national team in March 2014 while on loan at Doncaster which kept him on the sidelines for a year.
The 28-year-old ended last season by making 10 appearances for Colchester, helping them to stay in League One, but the number of games he missed because of injury could see Doncaster’s hopes of bringing him back to the Keepmoat Stadium dashed by red tape.
Dickov told BBC Radio Sheffield: “I’ve been in contact with his representatives and the problem that Bongs has got at the minute is his working visa in this country.
“Through the unlucky injury that he had and the amount of time he was out, he has not played the amount of games for the national team that is required and the amount of games in this country that is required.
“That makes it a problem for him getting his visa and it’s looking unlikely at the minute that it is something that could be sorted out. I know his representatives here and in South Africa are trying to sort it out.
“Bongs was fantastic for us, on and off the pitch, as a player and a person. He would definitely be one that we’d be interested in.
“I made the call to his agent at the end of the season just to find out what he was thinking because he finished it really strongly at Colchester.
“We were told then the main problem would be the visa and that’s an ongoing thing at the minute, and it’s still a problem for him.
“That’s not just disappointing for me but for Bongs too because he wants to stay in England.”