BRUSSELS (Reuters) - EU antitrust regulators on Tuesday opened a full-scale investigation into private equity firm Blackstone's (>> Blackstone Group LP) plan to combine its acetone tow with that of U.S. speciality material company Celanese (>> Celanese Corporation).

The companies unveiled the proposed merger of the world's No. 2 and 3 players in June, which would make it the new market leader in the supply of the material used in cigarette filters.

The European Commission said the deal may reduce competition in the acetate tow market, with the other two major rivals Eastman and Daicel unable to exert competitive pressure.

It said there was a greater likelihood of tacit coordination between tow suppliers as a result of the deal. The EU competition enforcer will decide by March 5 whether to clear or block the deal.

The companies can offer concessions to allay the regulatory concerns.

(Reporting by Foo Yun Chee; Editing by Alissa de Carbonnel)

Stocks treated in this article : Celanese Corporation, Blackstone Group LP