The US Department of Justice (DOJ) has approved Alaska Air Group's proposed acquisition of Virgin America for $4bn.

The approval was given after the completion of a review carried out by DOJ’s anti-trust division in relation with the deal.

According to the requirements imposed by the DOJ, Alaska Air Group has agreed to implement limited changes to its code-share agreement with American Airlines before completing the deal.  

"The expanded West Coast presence and larger customer base create an enhanced platform for growth."

Alaska Air Group and American Airlines were not required to make any changes to their other existing agreements, including interline or reciprocal loyalty agreements or any of Alaska's other airline partnerships.

In addition, Alaska was not required to divest any assets as a condition of DOJ clearance.

The company is further planning to settle a lawsuit filed by private plaintiffs in the US District Court in San Francisco in relation with the acquisition.

Alaska Air Group chairman and CEO Brad Tilden said: "With this combination now cleared for take-off, we're thrilled to bring these two companies together and start delivering our low fares and great service to an even larger group of customers.

"We remain confident in the merits of this transaction.

"The expanded West Coast presence and larger customer base create an enhanced platform for growth, which is good for investors, employees and especially customers, who benefit from more choices, increased competition and low fares."

The company currently owns Alaska Airlines and Horizon Air Industries.

Alaska Airlines and its regional partners flies 32 million customers a year across North America.