TORONTO - The World Health Organization and leading influenza research groups are investigating unpublished claims that the new H1N1 swine flu virus may have evolved in a laboratory, not in nature.

Bloomberg News is reporting retired Australian researcher Adrian Gibbs plans to publish a scientific report saying the never-before-seen virus may have evolved in eggs.

Eggs are used in laboratories and in vaccine manufacturing to grow up quantities of influenza viruses.

Gibbs apparently claims that the virus bears the hallmarks of having undergone `accelerated evolution' such as what happens when viruses try to adapt to growing in eggs.

The U.S. Centers for Disease Control has been studying Gibbs' claim and says it does not believe Gibbs is correct.

The CDC's Dr. Nancy Cox says her labs and others cannot find evidence to support the claim that the virus has undergone accelerated evolution.