The Financial Times said Providence had been in informal talks with Informa but that no offer had been made and no bid was likely above 500 pence a share.

Numis said a private equity bid would need to be pitched around 500 pence to succeed, representing a 30 percent premium on the price before the merger talks with UBM were announced.

"As a business built by acquisition/merger, Informa could be dismantled into more manageable pieces relatively easily in our view," Numis said in a note to clients.

"For example, Springer may enter a consortium to secure the Scientific assets."

Informa rejected a bid from Germany’s Springer Science + Business Media in 2006, saying at the time that the 630 pence offer undervalued the company. Springer is owned by private equity firms Candover and Cinven.

"Springer offered 630 pence for Informa in Oct 2006 and we therefore believe that they could become involved in a consortium given the significant (around 50 million pounds cost savings that could be achieved from the Academic businesses," UBS said in a note.

Other names linked with Informa include Apax which joined the Guardian Media Group to buy the specialist publishing and conference assets of Emap last year.

Informa declined to comment further on the approach and none of the private equity parties could immediately be reached for comment.

(Reporting by Mark Potter and Kate Holton; editing by Rory Channing)