Republican U.S. congressman Scott Perry of Pennsylvania, an ally of former President Donald Trump, has sued the Justice Department in a bid to stop investigators from searching the contents of his cellphone after it was seized this month.

Perry, who has helped spread Trump's false claims that the 2020 election was stolen from him through widespread voting fraud, was vacationing with his family on Aug. 9 when three FBI agents approached him with a search warrant to seize his cellphone.

The Justice Department has not explained its reason for seizing the device, but it appears to have been linked to its investigation into the Jan. 6, 2021, U.S. Capitol attack by Trump supporters and efforts by the former president's allies to overturn his 2020 election loss to President Joe Biden.

Perry's actions are being investigated separately by the U.S. House of Representatives committee looking into the Jan. 6 events.

In his lawsuit, filed in federal court in Washington on Aug. 18, Perry's attorneys said he asked the Justice Department not to seek a second warrant to search the cellphone's contents.

The phone, the lawyers said, contains information protected under what is called the U.S. Constitution's speech and debate clause, a provision that can shield legislative activities from legal liability, as well as material covered by protections for attorney-client interactions and spousal communications.

But they said Justice Department attorneys have threatened to seek a second warrant to search the phone unless both parties can reach an agreement to review the information from the device simultaneously to weed out material protected by the speech and debate clause.

Perry was in contact with Trump White House officials in the weeks before the Capitol attack that sought to prevent Congress from certifying the election results. During a congressional hearing in June, lawmakers heard testimony from a witness that Perry sought a pardon from Trump before he left office. The congressman has denied making such a request.