Spam email pretending to be from a hired killer is being sent out in an effort to blackmail recipients for up to $80,000.

The emails usually start with a cheery greeting of 'Good day' or have a subject line saying 'Read this to be safe and a new life in this new year' before going on to threaten the reader.

"Do not contact the police or FBI or try to send a copy of this to them, because if you do I will know and might be pushed to do what I have being paid to do, beside, this is the first time I turned out to be a betrayer in my job," the main text reads.

The emails then claim that the recipient has been stalked by a hired assassin for 10 days, but that the hitman is prepared to drop the contract if he is paid a total of $80,000 (£41,200).

The hitman claims that he will produce taped evidence of the contract to kill the email recipient on receiving an initial advance payment of $20,000.

"This is surely one of the sickest scams yet seen," said Graham Cluley, senior technology consultant at Sophos. 

"The intention of this email is quite clearly to frighten the recipient into coughing up a substantial amount of money or, at the very least, their bank account details."

Cluley said that the emails might be unnerving, but the only way to stop the distribution of these messages is for users to stop responding.

"Innocent, vulnerable people could be scared into believing that the contents of the email are truthful, while the not-so-innocent are arguably even more likely to be hoodwinked," Cluley said.