BRUSSELS, Nov 24 (Reuters) - EU antitrust regulators on Wednesday warned that Austrian plastics company Greiner's bid for Belgian rival Recticel may hurt competition and lead to price hikes as they opened a full-scale investigation into the deal.

Unlisted family-owned Greiner announced its offer in May but has faced opposition from Recticel which last month advised its shareholders not to sell their shares under Greiner's offer.

The European Commission said it had identified some preliminary concerns following an initial market investigation.

"The merged entity would hold high combined market shares in already concentrated markets, in particular locally in central European countries such as Austria, Germany, Poland and the Czech Republic," the EU competition enforcer said in a statement.

It also cited the impact on carmakers and set an April 8, 2022 deadline for its decision. (Reporting by Foo Yun Chee)