Spam emails describing West Africans dying of Ebola are being crafted to defraud unsuspecting victims.

This is according to antivirus software firm Kaspersky Lab, which says spammers are taking advantage of the Ebola outbreak by producing revitalised versions of an old "Nigerian Letter" scam format.

The 'Nigerian Letter' scams, or 419 scams, typically involve a fraudster promising victims large sums of money upon receiving up-front payments.

"An example of a 'Nigerian Letter' scam based on the Ebola virus topic that Kaspersky Lab experts came across is an email from a rich Liberian lady dying of Ebola," says Kaspersky.

"It contained a long story about her children who died from the virus and about a local medical centre that refused to help her. She was willing to donate more than $1.5 million to a recipient who would transfer this money to appropriate charities," adds the company.

Meanwhile, Kaspersky says authors of another fraudulent mail introduced themselves as 'employees' of the World Health Organisation.

Kaspersky says the fraudsters then "tried an unusual tack to attract attention – the reader was invited to a conference where Ebola would be discussed along with other medical issues."

"The recipient was also offered a job – paying 350,000 Euros a year – and a complimentary car to take up a position as the WHO's UK representative," adds the company.

Spammers typically exploit topics of news interest.

According to World Health Organisation (WHO), there have been over 9900 cases of the virus to date this year in West Africa.

Meanwhile, over 4,500 people have died of Ebola thus far this year.