LSE announced the proposed Refinitiv deal last year to broaden its trading business and make it a major distributor and creator of market data in a profitable and fast growing sector. It would also make it a rival to Bloomberg.

The European Commission has voiced concerns about the combined company's large market share in the trading of European government bonds because both LSE's MTS trading business and Refinitiv's Tradeweb are already market leaders.

The EU competition enforcer will send a statement of objections to the companies by mid October, the people said.

In some cases, companies prefer to wait for such a document so they can tailor concessions to the concerns and avoid giving up too much.

The Commission, which is scheduled to decide on the deal by Dec. 16, declined to comment.

Last month, LSE picked Euronext as the preferred bidder for its Borsa Italiana business, a sale aimed at addressing competition issues. Borsa Italiana, which LSE acquired in 2007, owns bond trading platform MTS.

Bloomberg was the first to report about the imminent EU charge sheet.

Refinitiv is 45%-owned by Thomson Reuters, which owns Reuters News.

By Foo Yun Chee