The three men and two women, who are all Bulgarian nationals with EU settled status, are charged with conspiring to collect information intended to be directly or indirectly useful to an enemy for a purpose prejudicial to the safety and interest of the state between 30 August 2020 and 8 February 2023.

Orlin Roussev, 45, of Great Yarmouth, Norfolk, Bizer Dzhambazov, 41, and Katrin Ivanova, 31, both of Harrow, northwest London, Ivan Stoyanov, 31, from Greenford, west London, and Vanya Gaberova, 29, from Acton, west London, appeared at Westminster Magistrates' court by videolink.

The five defendants are alleged to have conspired with "tasker" Jan Marsalek and unknown others, while Roussev's home is said to have been the operational hub for the espionage.

Marsalek was the Austrian former chief operating officer of the German payment company Wirecard, who became a wanted man in the country after the firm collapsed in 2020 in a fraud scandal. His exact whereabouts are unknown.

Outlining the allegations, prosecutor Kathryn Selby told the court: "The evidence reveals that all five were part of an organised network of UK-based Bulgarian nationals targeting several locations on behalf of the Russian state.

"It appears to be aimed at assisting the Russian state in hostile action against specific targets including the abduction of those targets."

The five defendants spoke only to confirm their names and dates of birth during the court hearing.

They were remanded in custody by deputy chief magistrate Tan Ikram ahead of their next appearance at the Old Bailey on 13 October.

All five were arrested by the Metropolitan Police counter-terrorism command in February under the Official Secrets Act.

Roussev, Dzhambazov and Ivanova were previously charged on 11 February with possession of false identity documents with improper intention under section 4 of the Identity Documents Act 2010.