LONDON - Hackers are targeting European charity groups working to help Ukrainian refugees fleeing the country following Russia's invasion, a senior Ukrainian cybersecurity official said on Wednesday.

Victor Zhora, the deputy chief of Ukraine's State Service of Special Communications and Information Protection, did not provide much further detail. His comments follow a report published earlier this month that alleged that unidentified hackers were trying to disrupt European government personnel involved in the managing the massive flow of refugees out of the country.

"We suppose that this is another proof of the spread of cyberwar to NATO countries," Zhora told reporters.

More than 3.5 million people have fled Ukraine since Russia invaded that country on Feb. 24, according to the United Nations refugee agency, the fastest-moving refugee crisis in Europe since the end of World War Two.

  - Reuters