Celebrity chef Gordon Ramsay's Claridge's restaurant has had a tonne of horse manure dumped on its doorstep.
Claridge's is located in central London
Protesters from People for the Ethical Treatment of Animals (Peta) were demonstrating against the chef cooking horse meat on his TV show The F-Word.
The animal rights group has accused Ramsay of mounting a TV ratings-grabbing "gimmick".
The programme said it gives paramount importance to the welfare of animals bred for consumption.
On Channel 4's The F-Word, journalist and broadcaster Janet Street-Porter explores the possibility of eating horse meat.
But a spokesman for Peta said: "Horses are often transported long distances in Europe without any food or water on extremely crowded trucks.
"Some horses arrive at the abattoir injured or dead. Those who survive are often still conscious when their throats are slit by abattoir workers."
Anita Singh, of Peta Europe, said: "Will it be a family dog next? Chickens, pigs, cows and horses all suffer fear and discomfort when they are robbed of their lives for nothing more than a fleeting taste or a TV rating."
A statement issued on behalf of The F-Word said: "Although perfectly legal to eat horse meat in Britain, the usual method of obtaining good quality product is to order from abroad.
"While the item includes a visit to rural France, where sales of horse meat are rising, it does not extend to a discussion on animals being transported beyond their country of origin.
"Neither does it seek to suggest anything other than the paramount importance of the ethical welfare of any animals bred for consumption."