A phishing email has stormed to the top of the virus lists for March, according to newly published monitoring data.

Kaspersky Lab said that Trojan-Spy.HTML.Bankfraud.ra was first detected on 27 February, but accounted for 32 per cent of all malicious programs detected by the company in March.

The security firm said that it has seen "millions of copies" of the malware sent around the world, and witnessed the email being mass mailed on several occasions.

The Trojan targets the Branch Banking and Trust Company, and attempts to lure users to fake websites registered by malicious users in Croatia and the Cocos (Keeling) Islands.

Of the other viruses in Kaspersky's top five, Bagle.gt makes up almost the same volume of infected mail traffic as last month.

The company believes that, if Bankfraud.ra disappears from the ratings in April, it seems likely that Bagle.gt will head the table.

Netsky.t and Netsky.q swapped places in March, one halving its presence in email traffic and the other doubling its share.

However, the authors of Warezov have not thrown in the towel; the most successful of their creations, Warezov.jx, made it to fifth place in March.

"There are no other new malicious programs in the March Top 20. However, Kaspersky Lab continues to see older malicious programs re-entering and remaining in the ratings," the firm stated.

"Of the four returnees in February, two have not only remained, but have increased their presence in infected traffic.

"Another six malicious programs returned to the rankings in March, including veterans such as Feebs.gen, Mydoom.m and Warezov.do."

Other malicious programs made up a significant 7.33 per cent of all malicious code found in email traffic, indicating that a number of other worms and Trojans are actively circulating.