The consolidation of Europe’s stock exchanges is frozen for another six months after a U.K. government agency announced two potential bids for London Stock Exchange PLC must be reviewed for their possible adverse competitive impact.

The U.K. Office of Fair Trading said yesterday that Britain’s Competition Commission should examine potential bids for the LSE by Amsterdam-based Euronext NV and Frankfurt-based Deutsche Boerse AG to see "whether either merger would lessen future competition in equities trading in the U.K.", according to the Wall Street Journal.

The Competition Commission has until Sept. 12 to release its review, though it could take an additional eight weeks.

A successful merger of LSE by either rival would lead to the creation of the world’s second-largest stock market, along with the New York Stock Exchange. But efforts to create an all-European stock market including London repeatedly have raised national, regulatory and market concerns.

Euronext, Deutsche Boerse and LSE announced recently that they would cooperate with the Competition Commission during its review.

The fact that experts resort to competition authorities makes it clear that Euronext faces a setback since it hoped to acquire LSE having no rivals. However, it also creates better opportunities to the operator of stock exchanges in Paris, Brussels, Amsterdam and Lisbon, as well as the options and futures market Liffe. Euronext Chief Executive Jean-François Theodore is trying to balance the interests of his potential target -- which has twice rejected bids from Deutsche Boerse that valued LSE at £5.30 ($9.93 or €7.68) a share, or £1.3 billion -- and his own shareholders, who have said they would balk at too rich a deal price, according to the Wall Street Journal.