Web wanderers are more likely to get a computer virus by visiting a religious website than by peering at porn, according to a new study.

"Drive-by attacks" in which hackers booby-trap legitimate websites with malicious code continue to be a bane, the US-based anti-virus vendor Symantec said in its Internet Security Threat Report.

Websites with religious or ideological themes were found to have triple the average number of "threats" that those featuring adult content, according to Symantec.

"It is interesting to note that websites hosting adult/pornographic content are not in the top five, but ranked tenth," Symantec said in the report.

"We hypothesise that this is because pornographic website owners already make money from the internet and, as a result, have a vested interest in keeping their sites malware-free; it's not good for repeat business."