Bwin has already received numerous offers from smaller rivals.
Gibraltar based gaming entertainment company 888 Holdings has put in a bid to buy online gambling giant and rival Bwin.Party.
Bwin has been up for sale since last year, with the company announcing that it had previously received numerous offers from smaller rivals including GVC Holdings, which is worth £280m.
888 Holding said it has entered into the game to compete against other bidders to takeover its bigger rival.
888 Holding said in a statement, "The Board believes that there is significant industrial logic in a combination of 888 and Bwin.Party, benefiting both companies and all shareholders and accordingly, has submitted a proposal regarding the acquisition of the entire issued and to be issued share capital of bwin.party for consideration comprising cash and 888 shares.
"Due to the size of the proposed transaction, it would require, inter alia, the approval of 888 shareholders. 888 shareholders representing approximately 59% of 888’s share capital have irrevocably committed, subject to customary conditions, to vote in favour of the proposed transaction."
Bwin was formed through a merger between London-listed PartyGaming and Austrian group Bwin, with the company experiencing a steady fall in earnings in the past three years.
The fall has been reportedly been triggered due to the weakness in the European poker market and blockage of gambling websites in Greece.
According to reports, bingo games operator 888 is worth £600m and is planning to boost its sports betting business.
The company previously hinted its interest in acquisitions, as it is benefitting with the industry shift from gambling to online betting.
If the deal materialises the merged business could be worth more than £1bn.
Following the offer Bwin.Party said in a statement, "The Board of bwin.party has noted the announcement made by 888 Holdings plc and confirms that it has received a proposal to acquire the entire issued and to be issued share capital of bwin.party.
"The Board and its advisers are conducting a detailed review of the proposals received to-date and will make a further announcement in due course, however there can be no certainty that these proposals will result in a transaction being completed."