Three in four victims of email investment scams continue to send money after police warn them they're being deceived, Queensland's top fraud cop says.

Detective Superintendent Brian Hay detailed the extent to which fraud victims became caught up in the scams as he called on the community to help rather than ridicule those who had been duped.

Investigators from Nigeria, Ghana and the United States yesterday joined with Queensland police at a conference south of Brisbane focused on tackling the global “fraud pandemic”.

Common email frauds feature requests for money to unlock a promised inheritance payment in the future or reap rewards from a business opportunity, while criminals also prey on vulnerable people through long-running romance scams.