EMI Group is understood to have opened its books up to a slew of potential suitors, including Warner Music Group.

Warner Music Group has been quiet of late, with regards to its evergreen interest in EMI. WMG had earlier put forward an offer, which valued EMI at roughly £2.1 billion ($4.1 billion). EMI rejected the deal in early March, after its board decided the terms were "inadequate."

As previously reported here earlier this month, private equity firms Fortress, Cerberus and One Equity are believed to be among the parties interested in EMI Group.

The equity firms had issued letters expressing their interest, ahead of making presentations to the EMI board.

All the parties are said to have until May 23 -- the day EMI publishes its financial year results -- to make fully financed, formal offers.

Representatives for EMI and Warner Music declined to comment.

A source at EMI, however, explains to Billboard.biz that the company is currently confined by London Stock Exchange confidentiality rules, which apply when a company is the target of a takeover approach.

On May 4, the company issued a statement which read, "Further to recent speculation, EMI Group plc confirms that it has received a number of preliminary indications of interest to acquire the company. There can be no certainty that any offer will ultimately be made." The company has yet to issue an official update.

Stock in EMI was down slightly in morning trading today to 245.25 pence.

EMI and WMG have been in and out of merger affairs since 2000. In 2006, the majors embarked on a series of tit-for-tat buyout offers, which ultimately dissolved when the European Court of First Instance annulled the European Commission's decision to clear the Sony BMG merger.