"Indeed, Muggles have been spotted searching the loch for the monster, and only prompt action by the Invisibility Task-force has so far prevented them finding it"
-- excerpt from "A Study into Muggle Suspicions about Magic", quoted in the Daily Prophet (DP1)
A group or division in the Ministry of Magic (DP1)
This Task-force's sole purpose is to hide the "Loch Ness Monster" from Muggle view (DP1)
The Invisibility Task-force is likely to be either a division of the Department for the Regulation and Control of Magical Creatures or come under the Office of Misinformation (which itself is unclassified as to department)