Governments agreed on Monday to restrict international trade in four shark species in a bid to save them from being wiped out due to rampant demand for their fins.

The 178-member Convention on International Trade in Endangered Species (CITES) voted at a meeting in Bangkok to control exports of the oceanic whitetip and three types of hammerhead shark, but stopped short of a full trade ban.

The move would require countries to regulate trade by issuing export permits to ensure their sustainability in the wild, otherwise they could face sanctions from CITES.

Asian nations led by Japan and China -- where shark fin soup is considered a delicacy -- tried in vain to block the proposals, which were pushed by countries including Brazil, Colombia and the United States.

The decision to add the species to CITES Appendix 2, which restricts cross-border trade, must still be formally approved by the conference's plenary session later this week.

Members would then have 18 months to introduce the trade controls.

The four species would join the great white shark, the whale shark and the basking shark, which already enjoy international trade controls.

The Bangkok meeting was also set to vote on a similar proposal for the porbeagle shark and the manta ray.

Humans kill about 100 million sharks each year, mostly for their fins, according to the UN Food and Agriculture Organisation (FAO), and conservationists are warning that dozens of species are under threat.

Ninety percent of the world's sharks have disappeared over the past 100 years, mostly because of overfishing in countries such as Indonesia, the FAO says.