Talks on a merger between United Business Media and Informa collapsed Tuesday after Informa said it had received an approach from a third party, thought to be a private equity bidder or bidders.

Analysts have said in recent weeks that an offer of about £2.2bn by private equity firms would make an attractive alternative to UBM’s all-share, nil premium proposition.

Providence has been in informal talks with Informa’s advisers but no offer has been made and no bid is likely above 500p. The shares closed Tuesday night at 470p.

A person involved in the talks said he did not know if Providence was the company that Informa was referring to in its statement, adding that the US-based fund would be unable to make such a bid alone. Providence declined to comment.

Possible partners for a bid would be Carlyle and Apax.

If confirmed, it would be the biggest private equity takeover offer for a listed company since the credit squeeze slammed the brakes on leveraged buy-out activity late last summer.

UBM, which owns PR Newswire and Building magazine as well as a large conferences business, and Informa, publisher of Lloyd’s List, were regarded as complementary business media groups and their merger had been seen as an apposite move in an atmosphere of restricted private equity movements.

The collapse of the proposed merger happened after the markets closed. UBM was the first to make a statement saying it had been unable to agree terms.

The movements of the Informa share price relative to UBM – it rose 30 per cent after the June 8 announcement of a possible merger while UBM remained flat – played an important part in the decision, a spokesman said.

Informa said discussions with UBM “remained at a very preliminary stage and no agreement on terms had been reached”.

UBM then said that its announcement had not been prompted by foreknowledge of the approach.

Informa’s shares were at 386p on June 8 when the merger was first proposed.