Nasdaq-listed Grab had in July announced its intention to acquire Trans-cab in a deal including a combined taxi and private-hire-vehicle fleet of more than 2,500 vehicles owned by Trans-cab.

The review is underway after the parties submitted necessary documents to the CCCS on Jan. 25, following the regulator's comment expressing inability to confirm that the deal would not pose competition concerns.

"Upon completion of the review, the CCCS will decide whether to issue a favorable or an unfavorable decision on the proposed acquisition," the CCCS said in a statement.

The commission found that Grab's proposed two-year duration to address competition concerns raised by CCCS was inadequate. Further, it said that Grab's self-policing monitoring mechanism was insufficient.

The regulator said during the review, Grab is allowed to propose revised commitments that would address the concerns raised.

(Reporting by Roushni Nair in Bengaluru; Editing by Dhanya Ann Thoppil)