Poker is increasingly popular with online gamblers

The UK's biggest online casino said it had made a "preliminary, non-binding approach to Empire".

Last month, Partygaming, which owns the Partypoker website, reported a 32% rise in quarterly revenue to $220m (�124m).

Empire, however, was forced to issue a profit warning last month after its users were blocked from using sites run by Partygaming.

Empire said its profits would be 10% below forecasts after Partygaming moved all its players to a new platform which blocked access from so-called skin sites.

Second approach

Any offer proposal would depend upon...a number of material pre-conditions, including due diligence and the prospects for Empire's business Partygaming Check Partygaming's shares Check Empire's shares

Partygaming did not say how much it was prepared to offer for Empire.

Press reports on Wednesday suggested that Partygaming was considering making a �400m bid for Empire, although analysts questioned whether the firm would be willing to pay this much.

In September, Empire said it had received a separate �790m approach from larger online rival Sportingbet. However, talks between both sides broke down later in the month.

In a statement, Partygaming said: "Any offer proposal would depend upon, in particular, Partygaming being satisfied as to a number of material pre-conditions, including due diligence and the prospects for Empire's business."