UPDATED Oct. 2, 2013, with comment from Zimmer.

(Reuters) – EU antitrust regulators will open an extensive probe into Zimmer (NYSE:ZMH) $13.4 billion bid for Biomet, concerned that the creation of the world’s 2nd-largest orthopedic products group may hurt competition, 3 people familiar with the matter said today.

The European Commission has been reviewing the deal between Zimmer and Biomet since August, after tabling it for a spell in June, and has set an Oct. 3 deadline for its decision, although this could be extended by 90 working days if it opens a broad investigation.

Zimmer may be forced to offer concessions to remove regulatory concerns unless it can convince the Commission that the deal would not reduce competition. In a prepared statement, the company said it still expects to close the merger during the 1st quarter of 2015.

The acquisition would make Zimmer the 2nd-largest seller of orthopedics products behind Johnson & Johnson (NYSE:JNJ), boosting its presence in the fast-growing sports medicine sector.

Anti-trust regulators in the U.S. and their counterparts in Japan are also looking at the Zimmer-Biomet deal.