Police and fire crews were in attendance at Loch Leven in Kinross on Sunday night.
All parties involved in what was described as a “police incident” were remaining tight-lipped as to the nature of the operation.
Police were initially called to the scene before requesting the assistance of fire crews around 7.45pm.
Appliances from Fife and Tayside attended at the scene along with a water rescue unit and there was speculation on social media that someone had fallen into the loch.
A spokesman for Police Scotland Tayside division said: “There’s nobody in the water.”
He said enquiries were ongoing at the scene.
But he could give no further details as to the nature of those enquiries.
Scottish Fire and Rescue were also unable to give details of their involvement in the apparent operation.
A spokesman for Fife control room said there was nothing to pass on to the media at this time.
Dundee control room stated it was a police incident and all enquiries should be passed to them.