In a departure from his long held stance of neutrality on political and conservation questions, Sir David makes clear his opposition to whaling in the report, Troubled Waters.

The issue of whalers' ability to kill humanely is central to the British and other conservation-minded nations opposing the resumption of commercial whaling. They say that if it cannot be achieved, then whaling should not resume.

The report shows that instantaneous death cannot be guaranteed and although the average time from being hit by an explosive harpoon to death is two minutes, many whales live much longer. Some are wounded and face an unknown fate.

In his foreword Sir David says: "Whales are highly evolved animals with all the sensitivities that that statement implies. They have a complex social life. They call to one another across the vast expanses of oceans.

"They are the largest animals that have ever existed, far larger than any dinosaur. There is nothing in the body of a whale, which is of use to us, for which we cannot find equivalents elsewhere." He says the report contains "hard scientific dispassionate evidence that there is no humane way to kill a whale at sea."

He quotes Harry Lillie, who worked as a ship's physician on a whaling trip in the Antarctic half a century ago: "If we can imagine a horse having two or three explosive spears stuck in its stomach and being made to pull a butcher's truck through the streets of London while it pours blood into the gutter, we shall have an idea of the method of killing.

"The gunners themselves admit that if whales could scream, the industry would stop for nobody would be able to stand it."

Sir David continues: "The use of harpoons with explosive grenade heads is still the main technique used by whalers today. "I hope that you will read the following pages and decide for yourself whether the hunting of whales in this way should still be tolerated by a civilised society."

The report, produced by the World Society for the Protection of Animals, draws on academic research and the expertise of a New Zealand government ballistics expert, the Humane Society of the United States, the Whale and Dolphin Conservation Society, and the RSPCA. Killing methods compare unfavourably to those imposed on the slaughter of land animals, the report says.

It says that claims by the whaling industry to be able to kill instantaneously vary widely between Japan and Norway, the two main whaling nations. The Norwegians claim to kill 80.7% instantaneously but the Japanese only 40.2%, although both are using the same techniques.

The main killing method is a harpoon that penetrates about 1ft into the whale before exploding, killing the animal with shock waves. If this fails a second harpoon or rifle is used. Average time to death is more than two minutes, the report says.

However it claims that "adaptations for diving" may make it difficult to determine whether the animals are dead. "Their sheer mass, complex vascular systems and specific anatomical features may also impede efforts to kill them swiftly and humanely."

The persecuted species

· There are more than 80 species of whales, dolphins and porpoises in the cetacean family

· Ten are listed as endangered and two critically endangered

· Eleven types are still hunted

· Killing great whales, 10 tonnes and above, is prohibited by the International Whaling Commission (IWC) but around 1,400 are expected to be hunted this year

· Smaller whales, like pilot whales and dolphins, are outside the scope of the IWC. Unknown thousands are killed

· Whales used to be caught for oil for lighting, heating, and lubrication; for use in making soaps and paints; and in processing textiles and rope. Bone was used to make corset stays, umbrella ribs, fishing rods, whips, carriage springs, skirt hoops, brushes, and nets. Meat was a byproduct

· Meat is eaten in Japan, Norway, the Faroe Islands, and by various indigenous peoples

· The principal method of killing is an explosive harpoon

· Norway kills between 550 and 650 minke whales a year; Japan 440 minkes in the Antarctic, 150 minkes, 59 sei, 50 Bryde's and 10 sperm whales in the Pacific.

· Iceland says it intends to kill up to 250 minke and sei whales annually for sale to Japan.