Indonesian authorities have seized about 3,000 shark fins that were about to be flown to Hong Kong, an official said Wednesday, a rare success in the battle against the illegal trade.

The fins from the oceanic whitetip shark, a species protected in Indonesia and banned from export, were seized last week at the international airport that serves the capital Jakarta, government official Rusnanto, who goes by one name, told AFP.

"The fins came from around 3,000 oceanic whitetip sharks which were caught in the waters around Java island," said the official who works for an agency that deals with fish, referring to Indonesia's main island.

He said the haul was worth one billion rupiah ($72,000) in Indonesia but would fetch several times that amount in Hong Kong, where shark fins are considered a delicacy.

Officials found the fins in boxes that were due to be exported, he said. The export company was being investigated, he added, without giving the name.

Hong Kong is one of the world's biggest markets for shark fin, which is often served as a soup at expensive Chinese banquets.

More than 70 million sharks are killed every year, according to environmental group WWF. Huge quantities are exported annually to Hong Kong, and most of those fins are then sent on to mainland China.

Conservationists have long been raising the alarm about shark-fishing in Indonesia, and point to signs that populations have been declining across the whole archipelago, which consists of more than 17,000 islands.

Efforts to crack down on the illegal trade have been hampered by weak law enforcement and a failure to offer poor fishermen alternative ways of earning a living.

The International Union for Conservation of Nature (IUCN) classifies the oceanic whitetip shark as "vulnerable" and says catches, particularly in international waters, are inadequately monitored.