Virgin boss Sir Richard Branson has hailed a move by Costa Rica to ban trade in shark fins as a "truly historic day".
The business chief has been campaigning against "barbaric" shark finning, including writing a letter to Costa Rica's president Laura Chinchilla, who has now declared zero tolerance towards the practice.
Ms Chinchilla, announcing the ban on imports of shark fins into the country, where finning is already forbidden, said: "It is a practice that Costa Rica does not accept and we want to send a clear signal on our opposition to such activities."
The government said there was evident overfishing, finning was wasteful as it only used a small proportion of the shark, was leading to the disappearance of shark populations and was depriving local people of a traditional food source.
The move by the central American country has prompted other states in the region to say they will also ban the import and export of shark fins, which are destined for the Chinese market where they are used for shark fin soup.
Sir Richard said: "It was a truly historic day, which all environmentalists are celebrating. There are other battles to be fought, but this was such an important start and an important message to the rest of the world on this barbaric thing."
He said that during finning: "Sharks are hauled into boats, their fins are cut off and sharks are thrown back to die a horrible death."
Costa Rica had been the heart of the supply chain to China, and the decision to ban the import of shark fins was an important start to efforts to end the slaughter of millions of sharks, he said.
He added: "It's great to get into a position where you can write a letter, get straight through to a president and make a difference. It was an incredibly happy day."
Having secured this victory with the organisation Ocean Elders, he said the focus now was on getting other countries to ban shark finning and the importation of shark fins, to educate people on the damage that shark fin soup was doing and encourage the Chinese and Koreans to ban it.