Elon Musk's SpaceX has sued the government over procurements multiple times. (Reuters)

Elon Musk's SpaceX is suing the federal government again.

But this time, it wants its protest of a government contract to stay under seal, meaning its allegations would not become public.

In a motion filed with the Court of Federal Claims on Friday, the company said the privacy was necessary because the suit contains "confidential and proprietary information and source selection information not appropriate for release to the public." SpaceX also filed its complaint against the government, with multiple exhibits attached, under seal.

Whether the complaint and other documents remain under seal will be up to the court to determine. The Court of Federal Claims hears suits against the federal government including bid protests and contract claims.

It was not clear from the filing what government procurement program the company is gearing up to challenge, but it comes as the Air Force is getting ready to award major launch contracts potentially worth billions of dollars to two companies. Last year, SpaceX lost out on an initial round of funding the Air Force awarded to help companies develop their rockets to meet the strict requirements of launching national security satellites.

Musk said the company had submitted a bid for that contract, but its proposal "missed the mark," according to a Pentagon review.

While SpaceX lost out on the funding, three of it competitors - the United Launch Alliance (ULA), Northrop Grumman and Blue Origin - shared more than $2 billion for their rockets.

SpaceX did not immediately respond to a request for comment. The court filing was first reported by GeekWire.

The Air Force is expected to pick two companies next year that would split Pentagon launches. But that procurement has already touched off a political battle in Washington.

Since it lost on the early round of funding, SpaceX had been concerned that it would be at a disadvantage when it came time to choose the two providers. Jeff Bezos' Blue Origin, meanwhile, has been lobbying the Pentagon and members of Congress to slow down the procurement since its rocket won't be ready to fly by next year. (Bezos owns The Washington Post.)

SpaceX has sued the government over procurements multiple times in the past. In 2014, it sued the Air Force over the last round of military launch contracts, saying it should be allowed to compete against ULA, a joint venture of Lockheed Martin and Boeing, that held a monopoly on the contracts for a decade.

Eventually, the Air Force and SpaceX settled the case, and SpaceX since has won several lucrative contracts.

Earlier this year, it also filed a protest over a $150 million contract that NASA had awarded to ULA for a robotic mission to the asteroids around Jupiter. Two months later, it withdrew the protest without saying why it reversed course.