Conservationists are urging the government to oppose plans to hunt an endangered species of marine turtle for its carapace.
International trade in tortoiseshell, taken from the hawksbill turtle, has been banned for decades. But Cuba is claiming that numbers have recovered sufficiently to withstand limited commercial exploitation.
The turtle's population around British overseas territories in the Caribbean is being studied by scientists from the University of Wales Swansea and the Marine Conservation Society (MCS).
But their results will come too late to inform the UK position before a vote on the Cuban proposals is taken at a Convention on International Trade in Endangered Species meeting in November.
A government spokesman said the UK was keeping "an open mind" on Cuba's plan before a dialogue meeting discusses the issue in the Cayman Islands in three weeks' time.
While this stance has surprised campaigners, the spokesman insisted: "Any future decisions will be based on sound science and a desire that any proposed trade should be properly regulated, sustainable and not detrimental to the conservation of the species."
The hawksbill turtle population crashed as it was hunted for its brown, yellow and amber shell. An illegal trade continues and demand is high in Japan.
Peter Richardson, species policy officer at the MCS, said that the government-commissioned assessment of the hawksbill would be complete by 2004. He expected the UK would oppose a change in the turtle's status until it had this data.
"There is no evidence to suggest the Caribbean turtle population has recovered enough to support large-scale international trade in hawksbill shells," he said.
Dan Evans, education coordinator at the Caribbean Conservation Corporation, said he was shocked the UK could entertain the idea of some form of commercial exploitation. He said the worldwide population of the species had been estimated in 1992 at just 8,000 nesting females.
"Once you create a limited legal market, you open the door to illegal trade and you'll go through the entire population fairly rapidly," he said.
But some conservationists support the Cuban plan, which would permit the sale of a stockpile of hawksbill shells as well as small, regular harvests.
Nicholas Mrosovsky, professor of zoology at Toronto University, said that the threat to the species had been exaggerated.
"Hawksbill turtles will be conserved if they're valuable and local people have a stake in their conservation," he said.