The East Suffolk Council in England announced the defacement of a new artwork that Banksy had created as part of his latest street works under the title of "A Great British Spraycation" in the towns of Suffolk and Norfolk.
The elusive artist, famed for his street art, recently paid a visit to Lowestoft, leaving behind a painting of a rat sitting on a deckchair.
But residents in the Suffolk town awoke on Sunday to the news that the new attraction had been daubed with white paint.
In a statement, the local Suffolk Council said: "We are naturally appalled that someone has chosen to behave in such a selfish and mindless way given how excited we all are by the appearance of these works here on the east coast. We are, however, hopeful that this particular work can be restored, and are engaging with specialists."
The council said that prior to the rat art being confirmed as a genuine Banksy it had placed an order for protective materials to safeguard the piece.
It added: "In the interim, we have also employed security patrols to visit each site and on this occasion. Our patrols actually interrupted the individual defacing this work and prevented any further damage occurring. We are very grateful for the huge goodwill of local people who are proud of these artworks, but we would kindly ask people not to try and repair the works themselves and to please leave this to professional restorers."