Two watchdog groups have sued Donald Trump over White House records, accusing the president of illegally destroying communications that must be preserved by federal law.

The suit filed Thursday against Trump and the Executive Office of the President by Citizens for Responsibility and Ethics in Washington (CREW) and the National Security Archive focuses on an auto-delete app reportedly being used for messages sent from the White House that erase messages after theyre read.

Such communications could involve correspondence among the president, aides, advisers, contractors, lobbyists and others. Theyre part of a historical record that belongs to the public and must be preserved, as mandated by the Presidential Records Act of 2014, notes the suit, which was filed in U.S. District Court for the District of Columbia. The law requires the preservation of communications in the White House and vice presidents office.

Yet evidence suggests that President Trump and others within the White House are either ignoring or outright flouting these responsibilities, the suit states.

The American people not only deserve to know how their government is making important decisions, its the law, CREW Executive Director Noah Bookbinder said in a statement. By deleting these records, the White House is destroying essential historical records .

CREW spokesman Jordan Libowitz told HuffPost that the only reason for the Trump administration to delete messages is to keep them secret from the American people. He said its part of a larger, troubling pattern of information suppression in the Trump administration, which also includes deletion of the presidents tweets.

The suit cites a vanishing tweet on Trumps account about meeting with U.S. generals at Mar-a-Lago. Such tweets, involving official government business and policy statements by the president, are also subject to the Presidential Records Act, the suit argues.

Trump repeatedly blasted Democratic rival Hillary Clinton during the presidential campaign for her use of a private email server while she was secretary of state, but those emails were still recoverable.

The lawsuit against Trump cites a report in The Washington Post that White House staffers use an app called Confide , which sends encrypted messages that self-destruct once theyre read. The Wall Street Journal also reported similar use of the encryption cloaking app Signal for White House messages . The use of the apps knowingly prevent the proper preservation of records, the suit charges.

Using encrypted messaging apps that prevent any kind of preservation raise serious concerns that presidential records are at risk, said Tom Blanton, director of the National Security Archive. Presidential records are not subject to the Freedom of Information Act while a president is in office. But they are accessible by law five years later provided they have been preserved.

The suit demands the records be preserved against efforts by the president and his staff that seek to evade transparency and government accountability.

The White House hasnt yet commented on the suit.

CREW also sued Trump in January, accusing him of violating the emoluments clause of the U.S. Constitution by collecting foreign income through his various businesses. The clause forbids a president from receiving payments from foreign governments. In one example, the Kuwait Embassy in February booked space and services for an event at Trumps hotel in Washington, D.C., that was estimated to cost as much as $60,000.

More than 190 Democratic lawmakers also sued Trump last week over the emoluments clause, saying he had accepted funds from foreign governments through his businesses without congressional consent in violation of the U.S. Constitution.