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GENEVA, Nov 23 (Reuters) - Health officials have failed to reach agreement on a new system to ensure developing countries benefit more from sharing avian influenza viruses used to develop vaccines, the World Health Organisation said on Friday.

"Nobody can fault you for not trying... It is so close yet so far away," WHO director-general Margaret Chan told the final session of a four-day meeting.

Officials would probably meet again in a smaller working group ahead of the WHO"e;s annual assembly in May, WHO spokesman Gregory Hartl said. But a more complete meeting would be needed afterwards to clinch a deal, he said.

The WHO agreed last May to revamp its 50-year-old system for sharing influenza virus samples and is seeking accord on new rules for sharing them with researchers and drug companies.

But Indonesia, the country hardest hit by bird flu, has said poor nations risked not getting the benefits of any vaccines developed from their virus samples.

It argues that countries who share bird flu virus samples should have full control of their use and access to vaccines developed from them.