CAIRO, Feb 29 (Reuters) - Abu Dhabi National Oil Company (ADNOC) said on Thursday it formally closed the acquisition of a 24.9% stake in Austria's Austrian oil and gas group OMV from Abu Dhabi sovereign wealth fund Mubadala Investment Company.

The financial terms of the deal were not disclosed.

"The transaction accelerates delivery of ADNOC's global chemicals growth strategy and reinforces its status as a responsible, long-term partner and growth-oriented investor," ADNOC said in a statement.

ADNOC has been flexing its muscles, taking on international oil companies and Gulf rivals in its pursuit of energy assets outside the United Arab Emirates.

(Reporting by Enas Alashray and Yomna Ehab. Editing by Jane Merriman)