Imported automobiles are parked in a lot at the port of Newark New Jersey, U.S., February 19, 2019. REUTERS/Eduardo Munoz

WASHINGTON (Reuters) - A conservative group has sued the U.S. government for access to a report on whether auto imports pose a big enough security risk to justify hefty tariffs on the sector, part of a growing chorus demanding a copy of the document.

Cause of Action Institute (CoA), a watchdog aligned with the conservative political activists David and Charles Koch, asked the District of Columbia Federal Court on Wednesday to require the Commerce department to hand over a copy of the report, which could unleash tariffs of up to 25 percent on imported cars and parts.

Last month, Commerce Secretary Wilbur Ross submitted the so-called “Section 232” national security report to President Donald Trump, starting a 90-day countdown for him to decide whether to impose the tariffs on millions of imports.

The Commerce department declined to comment.

The industry has warned that tariffs could add thousands of dollars to vehicle costs and potentially lead to hundreds of thousands of job losses throughout the U.S. economy.

The Commerce Department started its investigation in May 2018 at Trump’s request. Known as a Section 232 investigation, its purpose was to determine the effects of imports on national security. It had to be completed by February.

In the suit, CoA alleged the Commerce Department has missed deadlines to respond to Freedom of Information Act Requests it filed for the report on Feb. 18, a day after the report was sent to the White House.

Republican Senator Chuck Grassley, chairman of the Senate Finance Committee, has also sought a copy of the report without success, Politico reported.

Administration officials have said tariff threats on autos are a way to win concessions from Japan and the EU. Last year, Trump agreed not to impose tariffs as long as talks with the two trading partners were proceeding in a productive manner.