Nottingham Forest are considering legal action over Tottenham's interest in midfielder Morgan Gibbs-White, sources have told BBC Sport.
Forest are believed to be looking at whether a specific confidentiality agreement in the £60m release clause in Gibbs-White's contract has been breached.
BBC Sport reported on Thursday that Gibbs-White was set to have a medical on Friday as Spurs look to trigger that release clause.
Sources have told BBC Sport that Forest are furious at Tottenham's conduct in their pursuit of the England international, and they insist Forest's threat to take legal action is genuine.