Fraud committed against companies by their own employees has surged this year, new data suggest, providing fresh evidence that the recession is fuelling a rise in crime.

Whistleblower hotlines operated by The Network, a US group that provides compliance services to some of the world’s biggest companies – including Aviva, the UK insurer, Cisco and Yahoo, the US tech companies, and Delta, the US airline – have received a deluge of tip-offs about fraud in recent months.