"Black gold": Legal sales worth �100m a year.

But the Convention on International Trade in Endangered Species (CITES) said on Wednesday that reduced quotas agreed by Azerbaijan, Kazakhstan, Russia and Turkmenistan were satisfactory.

CITES suspended the multi-million-dollar industry in June 2001 to allow the four countries to survey sturgeon stocks and develop a common management plan for the grade two endangered species.

Certain sub-species such as the high-quality Beluga and Osetra were then considered near extinction.

At that time illegal sales of caviar - known in the region as "black gold" - were thought to be 10-12 times the declared harvest, which was estimated to be worth �100m a year.

'Fishing and corruption'

"For the first time, the Caspian Sea's wild sturgeon populations are being managed through a unified system rather than through competing national systems," said CITES Secretary-General Willem Wijnstekers, announcing the lifting of the ban.

"This has enabled the region's governments to demonstrate that sturgeon numbers are indeed stable or, in some cases, increasing," he said.

A survey done while the ban was in force, however, did show an abnormally large proportion of young sturgeon in comparison to the older fish which produce the fish eggs.

Mr Wijnstekers said the lifting of the ban would raise money to fund the development of sturgeon hatcheries to help secure the species' long-term survival.

But he said the agreement did not mean the crisis over sturgeon stocks was over.

"In particular, greater efforts are needed to combat illegal fishing and corruption," he said

Together with Iran, which was not subject to the ban, the countries agreed to limit their exports to 142 tonnes this year - nearly a 10% reduction from last year's levels.