Competition regulators from both sides of the Atlantic have given the green light to Delta Air Lines’ plan to buy almost half of Virgin Atlantic.

Both the US Justice Department and the European Commission said the deal does not pose an antitrust threat.

They concluded that Delta and Virgin Atlantic will still be competing against a strong alliance between British Airways and American Airlines, as well as other carriers.

“After a thorough investigation of the competitive effects of the proposed equity investment and joint venture, the antitrust division concluded that the facts and circumstances did not warrant further investigation or action,” the Justice Department said.

The agreement still needs approval from the US Department of Transportation, which Delta hopes to secure later this year.

Delta wants to buy a 49% stake in Virgin Atlantic for $360 million. This would enable the carriers to sell seats on each other’s flights, giving Delta a way to expand flight options between New York and Heathrow, the busiest aviation route in the world.

The US carrier’s 10 daily non-stop transatlantic flights to the UK would be added to the 21 operated by Virgin Atlantic under its summer 2013 schedule.

Delta’s current share of the US-UK market is about 8%, with the joint venture enabling this to grow to 25%.

The two carriers announced the deal in December, saying the purchase would allow the US carrier to expand its access to capacity squeezed Heathrow.