"I think we would do well not to underestimate the difficulties" involved in any exploitation of the high north's natural resources, Stubholt told Thomson Financial News in a telephone interview.

A team led by David Haussler of the Howard Hughes Medical Institute in California, compared the human genome with that of mammals including other primates. They reported the results in Nature.

Osterhaus said the findings, reported in the science journal Nature, did not exclude the possibility that chlamydia or other infections could increase the severity of the illness in some people.