Federal agents delivered subpoenas to some reporters' homes demanding they appear before a federal grand jury investigating a potential crime, the Times said.

The paper had published stories alleging that the Qatari-gifted plane was not secure enough, and the Secret Service urged Trump to switch planes on his way home from a Nato summit in Turkey.

The Justice Department told the BBC it was investigating illegal leaks, adding: "Reporters are not the targets, those leaking classified information are."

David McCraw, the Times's top newsroom lawyer, called the summons a "brazen act" and "nothing more than an attempt to prevent the public from knowing what is happening in their country by intimidating journalists from doing their jobs".