Many have been transported for hours in open boats and one dolphin, which was being trained to perform tricks for prospective buyers, was recently killed by a saltwater crocodile.

Nearly 60 dolphins are in pens on the island of Gela off the capital, Honiara, and locals say they have seen dozens more being held elsewhere. The scheme is believed to involve a German and a Canadian who have links with a small resort on Gela.

In some parts of the Solomons is it taboo to harm dolphins, partly because of an ancient belief that people with magical powers can turn themselves into the animals.

In nearby Australian territorial waters, the catching of dolphins is illegal and there has been a crackdown on such operations in other parts of the Pacific, including neighboring Vanuatu.

The legal position is unclear in the Solomons, where five years of violence and economic collapse have paralyses much of the administration.

As well as the dolphin scheme, the chaos has allowed foreign companies to engage in damaging logging and fishing operations without proper monitoring or export controls.

"I am worried about the welfare of the dolphins," Philip Jionisi, of the Solomon Islands Civil Society Group, said yesterday. "I hate to see this. They should be free because the moment we keep them in captivity we are spoiling them."

He said locals working for the foreign operators have said privately that the dolphins are be flown overseas and sold.

The Greenpeace representative in Honiara, Geoffrey Dennis, said that in the past few weeks two interested buyers had inspected the dolphins.

He said there were also fears of environmental damage from the dynamite used to catch the fish needed to feed the dolphins.