The Russian music site sells copyrighted material for as little as 3p per track and claims to pay licence fees to the Russian Multimedia and Internet Society.
However, the BPI said that the Russian body is not officially recognised and that UK copyright holders receive no fees for the tracks that are sold.
"The Russian Multimedia and Internet Society is not an officially licensed body and is not recognised as a trade association, so it is completely illegal, " BPI spokesman Matt Phillips told vnunet.com.
"If you are selling music and it is on-demand, such as a stream or a download or a tethered download, you need to go to the copyright holder and get a licence."
Phillips explained that Allofmp3.com is already under investigation in Russia and had been targeted by the US.
"Our equivalent body in Russia has brought a case against the directors of the site which is an ongoing criminal prosecution as I understand it. I think the US is putting quite a bit of pressure on the Russian authorities to enforce the law," he said.
The BPI will serve Media Services, which runs Allofmymp3.com, with a writ later this week.
"The High Court is now working with the Russian court to ensure that those proceedings are issued," said Phillips.
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