July 30 (Reuters) - Alaska Air Group ( ALK ) has agreed

to extend the review period for the proposed $1.9 billion

acquisition of rival Hawaiian Airlines amid antitrust

scrutiny from the U.S. Department of Justice, the carrier said

in a filing on Tuesday.

"Our airlines have mutually agreed with the DOJ on a brief

extension of the formal review period until August 15," Alaska

Air Group ( ALK ) said.

The deal, announced last year, has been under antitrust

review and both carriers said in March they "have been working

cooperatively with the DOJ and expect to continue to do so".

Shortages of new planes, jet engines and pilots have spurred

U.S. airlines to pursue growth through acquisitions, putting

them in the crosshairs of anti-trust regulators who have

generally been wary of mergers between smaller airlines.

The takeover would give Alaska Air ( ALK ) control of more than 50%

of the market for flights to Hawaii, one of the world's top

holiday designations.

The airlines, in March, entered a timing agreement with the

DOJ, under which the carriers agreed not to consummate the deal

within 90 days after submitting antitrust-related information.