Forsyth (right) in action against Birmingham City
Olsson has since established himself as a regular at Pride Park in the Scotland international's absence with a cruciate ligament injury.
Derby signed Olsson (right) from Blackburn in January
However, with only Forsyth for cover, new Derby manager Nigel Pearson may be reluctant to lose the 27-year-old, who recently made his comeback for the first team.
Blackburn received a reported £5.5 million from Grant Hanley's recent departure to Newcastle United and HITC Sport understands they will look to spend some of that money on Nottingham Forest centre-back Matt Mills.
Mills is being lined up to replace Hanley at Ewood Park
And further reinforcements may be required, with a number of clubs said to be keen on Hanley's former defensive partner Shane Duffy.
Duffy is thought to be a wanted man
Forsyth has made 127 appearances for the Rams since joining from Watford three years ago, initially on loan. The Dundee product has also enjoyed temporary spells at Montrose, Arbroath and Bradford City.