IPL is warning its shareholders that they may be approached by Melbourne based Hassle Free Share Sales Pty Ltd, which recently obtained their contact details from share registers the companies were legally obliged to provide.

It follows a similar warning in recent weeks from sugar and ethanol firm, CSR.

"We know Hassle Free has already approached some of our shareholders with offers substantially below our current market price," IPL company secretary Kerry Gleeson said.

Hassle Free offered one IPL shareholder $103.87 per share for 330 shares, which traded at $158.34 on the ASX on the same day as the offer.

"Had the shareholder accepted that day, he would have lost $17,975.10 or a third of the value of the shares," Ms Gleeson said.

The Hassle Free Shares attempt follows similar schemes from notorious businessman David Tweed, who has also made unsolicited offers to IPL shareholders.

IPL advised shareholders to seek independent financial advice if they received offers from any other potential purchaser.

"As the law currently stands, IPL and other public companies cannot prevent any party obtaining a copy of our share register, which contains information about individual shareholders," Ms Gleeson said.