Organisers of the FHM 100 Sexiest Women vote had to clamp down on the voting after they noticed that singer Andrea Corr shot up more than 100 places in the voting in just a matter of hours.
They traced the problem back to an unofficial website dedicated to the band. The site was encouraging fans to use a technique for multiple votes.
Andrea whose two sisters and brother are also in the band was initially down in 257th position.
However, she rose to 151 overnight, which made alarm bells ring with compilers.
A spokeswoman for the magazine said: "As it's only one vote per person, FHM were naturally suspicious, and after some investigation traced it back to the source."
Chart stars Holly Valance and S Club singer Rachel Stevens are thought to be among the frontrunners for the overall title of the world's sexiest woman.
Voting closes at the end of this month.
The 2002 poll was won by Russian tennis beauty Anna Kournikova, who was followed by S Club 7 singer Rachel Stevens and singer Britney Spears.
Andrea Corr came in at number 79 last year.
FHM said of the Dundalk beauty at the time: "The woman all Dublin barmaids turn into at around 10.30, Andrea Corr is a living Guinness-induced sex hallucination. She is the wholesome product of a rural Irish background and has the endearing habit of sucking her thumb."