German police are investigating the possible poisoning of exiled Russians after a journalist and an activist reported health problems following a Berlin meeting of dissidents, a spokesman for the force said on Sunday.

The probe is being handled by the state security unit, a specialised team that examines cases related to terrorism or politically motivated crimes, a Berlin police spokesman told AFP.

“An investigation has been opened. The probe is ongoing,” he said, declining to provide further details.

Russian investigative media outlet Agentstvo this week published a report saying two participants who attended a April 29-30 meeting of Russian dissidents in Berlin experienced health problems.

The Berlin meeting was organized by exiled former oligarch turned Kremlin critic Mikhail Khodorkovsky.

One participant, identified as a journalist who had recently left Russia, experienced unspecified symptoms during the event. They said the symptoms may have started earlier. 

The report added that the journalist went to the Charite University Hospital in Berlin — where Kremlin critic Alexei Navalny was treated after being poisoned in August 2020.

The second participant mentioned was Natalia Arno, director of the NGO Free Russia Foundation in the United States, where she has lived for 10 years since having had to leave Russia.

Arno had attended the Berlin meeting of dissidents before travelling to Prague, where she experienced symptoms and discovered that her hotel room had been opened, Agentstvo reported.

Leaving the next day for the United States, she contacted a hospital there as well as the authorities.

Arno detailed her problems — “sharp pain” and “numbness” — on Facebook this week, saying the first “strange symptoms” appeared before she arrived in Prague. She said that she still had symptoms but felt better.

Contacted by AFP, Czech authorities said they did not have information on the case. 

‘Inconclusive tests’

The Agentstvo report also said former U.S. ambassador to Ukraine John Herbst, now senior director of the Atlantic Council’s Eurasia Center, suffered from poisoning symptoms a few months before Russia invaded Ukraine.

The Atlantic Council think tank confirmed Herbst showed symptoms that could be those of poisoning in April 2021 but medical tests were inconclusive.

It added that it worked with US federal investigators who took a blood sample but the lab results had failed to detect toxic compounds.

Herbst has since recovered to full health, it said.

Several poison attacks have been carried out abroad and in Russia against Kremlin opponents in recent years.

Moscow denies its secret services were responsible.

But European laboratories confirmed Navalny was poisoned with Novichok, a Soviet-made nerve agent.

The nerve agent was also used in an attempted murder in 2018 of former double agent Sergei Skripal and his daughter in the English city of Salisbury.

The Skripal case further exacerbated already dire relations between London and Moscow since the 2006 radiation poisoning death in the British capital of former spy Alexander Litvinenko.