Several New York Times journalists were summoned to testify under oath after they reported alleged security concerns involving President Donald Trump's new Air Force One plane, the US newspaper said.

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".

The subpoenas - a legal requirement from a court or government agency that compels a person to appear or produce records or evidence - say the reporters' testimony is required "in regard to an alleged violation of federal criminal law", the Times reported.

The summonses require the reporters to appear before a grand jury in Manhattan on Wednesday, the Times said. Grand jurys are composed of members of the public and convened by the US government to examine evidence and decide if there is enough to charge a person or persons with a crime.

The New York Times reported on security concerns about the president's plane citing unnamed sources. While speaking to media about classified information is a crime, the US Constitution protects the freedom of the press to report information in the public interest.

"We value and appreciate the important role that the press plays in this country, but DoJ also plays an important role to make sure that the people entrusted with our nation's secrets do what they're supposed to do with that information, which means not sharing classified information," the Justice Department (DoJ) said in a statement provided to the BBC.

The Times reported on Wednesday that while Trump flew to the Nato summit in Turkey on the new Air Force One, he left the summit on an older plane on the advice of the Secret Service. The next day, the newspaper reported that security officials were concerned the newer plane did not have advanced security features, including antimissile capabilities.

"Our journalists report the facts and advance the American public's right to know how their government is operating and their taxpayer dollars are being used," McCraw, the Times' lawyer, said.

Other outlets published similar reports, including CBS News, the BBC's US news partner. A former US government official told CBS that there was not enough time or money for the plane to be updated with the security requirements to serve as Air Force One.

While these reports were surfacing, tensions with Iran over a negotiated ceasefire deal were growing, and the US was launching strikes.

Trump brushed off concerns about the plane when asked by reporters this week and said: "I have a threat all the time. I'm No. 1 on their list".

Last month, Trump unveiled the new Boeing 747-8 jet that the Qatari government donated last year as an "unconditional" gift to the US to act as the new Air Force One.

The luxury jumbo jet was modified to transport the president and included upgrades in security, mission communications, logistics support, and advanced technology, the Air Force said. Any potential threats identified with the use of previously owned aircraft were "neutralised" in the new one, it added.

It has been valued at an estimated $400m (£300m).