Various reports suggest that Providence Equity is the company behind the approach for the Lloyd's List publisher, although The Times claims Providence has a consortium behind it.
Informa put out a statement last night simply saying that it has received a further approach from a third party.
Among the other names to have been linked with Informa are Candover and Cinven, owners of academic and business publisher Springer.
UBM ignited private equity interest in Informa by making an approach earlier this month, but has effectively been priced out of the picture by the increased value the stock market has put on its desired partner.
Since June 9, Informa's share price has risen 16.5% to 443.25p, while UBM's has stayed flat at around 605p. This has made UBM's nil-premium all-share merger proposal unworkable.
UBM said last night it had been unable to agree terms with Informa "that would be in the best interests of UBM shareholders".
The merger would have brought together UBM titles such as Property Week, Music Week and Farmer's Guardian with Informa's Lloyd's List and wide range of academic journals. Both companies have extensive events, exhibitions and data businesses.
UBM has reserved the right to make an offer for Informa in the event of a third party making an offer.
Analysts have suggested that private equity bidders could afford to pay 500p per share for Informa