WASHINGTON, United States — An unidentified impostor used artificial intelligence (AI) to imitate United States (US) Secretary of State Marco Rubio and contact foreign ministers, a US governor and at least one member of Congress, according to media reports.

The Washington Post reported Tuesday that the imposter utilised messaging app Signal and text messages to send AI-generated content that mimicked Rubio’s voice and writing style.

The report, which was updated around 6:00 am Tuesday and cites a July 3 cable sent by Rubio’s office, said the authorities do not yet know the identity of the impersonator, but they believe the culprit was probably attempting to manipulate powerful government officials “with the goal of gaining access to information or accounts”.

Citing also the Trump administration’s “extensive” use of messaging app Signal, the report said the impersonation campaign began in mid-June when the impostor created a Signal account using the display name “Marco.Rubio@state.gov” to contact unsuspecting foreign and domestic diplomats and politicians.

The display name is not his real email address.

“The actor left voicemails on Signal for at least two targeted individuals and in one instance, sent a text message inviting the individual to communicate on Signal,” said the cable.

Hany Farid, a professor at the University of California at Berkeley who specialises in digital forensics, said operations of this nature do not require sophisticated actors, but they are often successful because government officials can be careless about data security.

“This is precisely why you shouldn’t use Signal or other insecure channels for official government business,” he said.

In commenting on the cable, the State Department told the Post it would “carry out a thorough investigation and continue to implement safeguards to prevent this from happening in the future”.