BRUSSELS (Reuters) - Luxottica (>> Luxottica Group) and Essilor (>> Essilor International) have not offered any concessions to allay EU antitrust regulators' concerns over their proposed 46-billion-euro (40.9 billion pounds) merger, increasing the possibility of a lengthy EU investigation into the deal.

Italian eyewear maker Luxottica, which owns brands such as Ray-Ban and Oakley, and French lens manufacturer Essilor had until Sept. 19 to offer concessions after the EU competition enforcer expressed its reservations about the deal to the companies last week.

The European Commission recognises if the parties to a merger have made concessions. However, the filing on its website shows that Luxottica and Essilor had not done so.

Unless they managed to appease the Commission at last week's meeting, it is likely that the regulator will open a full-scale investigation lasting about four months following a preliminary review that ends on Sept. 26.

Some companies prefer to offer concessions during this phase after getting a better idea of the regulator's concerns.

The deal, which will combine the world's largest maker of spectacles with the world's top lens-maker, Essilor, has triggered worries among retailers and competitors that the merged company may have too great a control of valuable brands and prescription lenses.

Both Luxottica and Essilor declined to comment on the EU enforcer's concerns. U.S. regulators are also examining the deal, which received the green light from New Zealand authorities earlier this month.

(This story was refiled to delete erroneous advisory, no change to story text)

(Reporting by Foo Yun Chee, additional reporting by Sudip Kar-Gupta in Paris and Valentina Za in Milan; editing by Philip Blenkinsop and Louise Heavens)

By Foo Yun Chee

Stocks treated in this article : Essilor International, Luxottica Group