WASHINGTON: The mysterious so-called Havana Syndrome symptoms experienced by US diplomats in recent years have been linked to a Russian intelligence unit, according to a joint media investigation released on Monday.

Havana Syndrome was first reported in 2016 when US diplomats in Cuba`s capital reported falling ill and hearing piercing sounds at night, sparking speculation of an attack by a foreign entity using an unspecified sonar weapon.

Other symptoms including bloodynoses, headaches and vision problems were later repor te d by emba ssy staff in China, Europe and the US capital Washington.

The diplomats may have been targeted by Russian sonic weaponry, according to the joint report by The Insider, a Russia-focused investigative media group based in Riga, Latvia,Germany`s Der Spiegel and CBS`s 60 Minutes.

The year-long investigation `uncovered evidence suggesting that unexplained anomalous health incidents, also known as Havana Syndrome, may have their origin in the use of directed energy weapons wielded by members of (the Russian GRU) Unit 29155,` the report said.

Russia`s 29155 unit is responsibleforforeign operations and has been blamed for several international incidents, including the attempted poisoning ofdefector SergeiSkripal in Britain in 2018.

The investigation also reported that senior members of Unit 29155 received awards and promotions for work related to the development of `non-lethal acoustic weapons`.

Russia dismisses report Moscow dismissed the allegations as `groundless` on Monday.

`This is not a new topic at all; for many years the topic of the so-called `Havana Syndrome` has been exaggerated in the press, and from the very beginning it was linked to accusations against the Russianside,` Kremlin spokesman Dmitry Peskov told reporters when asked about the report.

`But no one has ever published or expressed any convincing evidence of these unfounded accusations anywhere,` Peskov said. `Therefore, all this is nothing more than baseless, unfounded accusations by the media.

A US intelligence investigation whose findings were released last year found that it was `very unlikely` a foreign adversary was responsible for the ailment, first reported by US embassy officials in the Cuban capital Havana in 2016.

Washington closed its Havana immigration office in 2018 under a US policy shift towards Cuba andalso in response to fears at the time that the Havana Syndrome` was a result of a microwave or other electronic attack.

US intelligence also said in 2022 that intense directed energy from an external source could have caused some cases of Havana Syndrome, officially known as anomalous health incidents (AHIs).

Washington announced the reopening of its immigration office in Havana in August 2023.

The joint investigation suggests the first cases of Havana Syndrome may have occurred in Germany two years earlier than the cases reported in Havana in 2016 that gave the syndrome its name.

`There were likely attacks twoyears earlier in Frankfurt, Germany, when a US government employee stationed at the consulate there was knocked unconscious by something akin to a strong energy beam,` the report said.

The New Yorker reported in July 2021 that about two dozen US intelligence officers, diplomats and other government officials in Austria had reported problems similar to the Havana Syndrome since President Joe Biden took office the same year.

The United States deployed medical and scientific experts to study the alleged attacks and those affected have been extensively examined to try to understand their afflictions.-Agencies