Leading Kenyan conservationist and politician Richard Leakey has called for a complete ban on the trade in ivory to be re-imposed.

On Sunday, five countries from southern Africa will lobby for permission to sell a limited amount of ivory.

They will put their case to Cites - the United Nations Convention on International Trade in Endangered Species - which meets in Chile.

Botswana, Namibia, South Africa, Zambia and Zimbabwe all claim that they have too many elephants and want to be able to sell stockpiled ivory.

I just don't think we can control the black market

Richard Leakey

But Dr Leakey told BBC HARDtalk that even a limited sale of ivory would lead to problems. He said: "It's not because I have any intrinsic problem with people using ivory - I just don't think we can control the black market."

Ivory stockpiles

The trade in ivory has been banned since 1999.

In 1999, Cites agreed to a one off-sale of nearly 50 tonnes of stockpiled ivory.

Dr Leakey warned that this limited sale had simply allowed the black market to expand in order to meet demand.

He said: "What is being allowed is the trade in ivory, country by country, quota by quota.

"It has opened up the spectre of legal trade in ivory and I believe this has led to an increase in the illegal trade."

National election

The career of Dr Leakey has been as controversial as it has been diverse.

He has campaigned against corruption both in government and opposition and remained a perpetual thorn in the side of the current Kenyan President, Daniel arap Moi.

But after 24 years in power, President Moi, is constitutionally obliged to step aside for a new leader.

Earlier this month he suspended parliament ahead of elections to be held on 27 December.

I'm absolutely certain Kenya's not a lost cause

Richard Leakey

Dr Leakey told Tim Sebastian that he was optimistic that a new leadership could completely stamp out corruption in the country.

He said: "All it needs is a government leader and government ministers who will say enough is enough and do something. I'm absolutely certain Kenya's not a lost cause."

And he added: "I think as a Kenyan we're probably seeing one of the best moments in our history since we gained independence."

This interview can be watched in full on Wednesday 30 October on BBC World and BBC News 24 at the following times:

BBC News 24 (times shown in BST) 0430, repeated 2230

BBC World (times shown in GMT) 0330, repeated 0830, 1130, 1530, 1830, 2330