The Pentagon has told journalists they must agree not to disclose unauthorised information or else risk losing access to the building.

The change is among several new restrictions, which also seek to impose limits on the movement of journalists within the facility, which is home to the Department of War, formerly known as the Department of Defence.

It follows a series of leaks in recent months.

Pete Hegseth, who was recently given the new title of Secretary of War, said on social media: "The 'press' does not run the Pentagon — the people do. The press is no longer allowed to roam the halls of a secure facility. Wear a badge and follow the rules — or go home."

The new restrictions were set out in a briefing note sent to members of the press, which they will be required to sign in order to maintain their Pentagon press credentials.

The department said it "remains committed to transparency to promote accountability and public trust".

But it added: "DoW information must be approved for public release by an appropriate authorising official before it is released, even if it is unclassified".

It asks signatories to acknowledge that determinations on press credentials for the building "may be based on the unauthorised access, attempted unauthorised access, or unauthorised disclosure" of classified national security information, or information designated as controlled unclassified information.

"The guidelines in the memo provided to credentialed resident media at the Pentagon reaffirms the standards that are already in line with every other military base in the country," said Chief Pentagon Spokesman Sean Parnell in a statement. "These are basic, common-sense guidelines to protect sensitive information as well as the protection of national security and the safety of all who work at the Pentagon."

Democratic lawmakers and members of the press have denounced the edict.

The National Press Club, an organisation for journalists in the US, called it "a direct assault on independent journalism at the very place where independent scrutiny matters most: the US military".

Senator Jack Reed, a Democrat and the ranking member on the Senate Armed Services Committee, called the restrictions "an ill-advised affront to free speech and freedom of the press".

Speaking to the media on Saturday, Trump dismissed the impact the restrictions would have on freedom of the press.

"Nothing stops reporters," he said.

Hegseth has previously come under scrutiny for his own handling of sensitive information after it was revealed he shared details about the bombing of Yemen on a group chat that included a reporter in March. Former national security advisor Michael Waltz, who was recently confirmed as the US's ambassador to the UN, had invited the journalist to the chat inadvertently.

The administration reacted angrily in June when a leaked intelligence report appeared to contradict statements it had made about the damage caused by US strikes on Iran's nuclear programme.