Attempts to put 60 tons of ivory – worth up to £15million – on the market was last night causing friction on the eve of the Convention on International Trade in Endangered Species in the Netherlands.

Ivory sales have been banned worldwide since 1989 but up to 20,000 elephants have been slaughtered illegally over the past two years for their tusks.

Namibia and Botswana want to sell Japan stocks of ivory from elephants that have been culled or have died naturally. British officials say they will look at scientific evidence before voting on whether to oppose the sale.

China will be lobbying nations at the convention to see if it can import legal ivory for its crafts and souvenir industry, saying it wants to become an authorised trader in confiscated ivory if stocks are sold.

The Environmental Investigations Agency last week published a report accusing the Chinese of being behind a vast illegal ivory trade. Its US president Allan Thornton said: “China’s claim to be planning a ‘green Olympics’ in 2008 will be severely tainted unless it acts to ban the domestic ivory trade.”