Doidge is said to be a target for Sunderland before August 9's deadline.
Sky Sports claim both Sunderland and Aberdeen are interested in the 25-year-old striker after he scored an impressive 25 goals in all competitions, as well as creating six, last season.
Since joining Forest Green in the summer of 2016, Doidge has found the back of the net 52 times in just 93 league and cup outings and his goalscoring heroics have certainly not gone unnoticed.
Cooper retaliated to reports that both Sunderland and Scottish Premiership Aberdeen were keen on the former Dagenham & Redbridge striker, stating that no approach had been made but did disclose that Doidge has changed his agent.
“It’s pure speculation. We haven’t had any contact from another club about Christian and until that happens then there’s nothing to be said about it,” said Cooper.
“Christian’s got a new agent, so he’s obviously going to work as you’d expect and fair play to him on that, but we’ve had no contact with any club.”
Sunderland are in desperate need of a striker, despite luring Jerome Sinclair to the Stadium of Light on loan from Premier League side Watford.
The club remain in the hunt for Bradford City forward Charlie Wyke, as well as being linked with a move for experienced Sheffield United star Billy Sharp. But Jack Ross is yet to add to his signing of Sinclair in the final third.
Doidge has two years remaining on his contract at the New Lawn, with cash-rich Forest Green making him one of their highest earners.
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