A sixth member of a suspected Russian spy ring has pleaded not guilty to conspiracy to conduct espionage in the UK.

Tihomir Ivanov Ivanchev, 38, has been charged with conspiring to collect information which could be harmful to the “safety and interest of the state” on behalf of Russia.

The Bulgarian national, of Acton, west London, appeared at the Old Bailey on Thursday, where he entered a plea of not guilty.

Ivanchev is accused of being part of an organised network conducting surveillance against several identities or locations in order to assist the Russian state in carrying out hostile interference.

He was arrested on February 7 as part of an investigation led by the Metropolitan Police’s Counter Terrorism Command.

It means there are now active criminal cases against six Bulgarians.

The other defendants, three men and two women, who all have addresses in the UK, will stand trial in October accused of conspiring to gather information that would be useful to an enemy between August 2020 and February 2023.

They are: Orlin Roussev, 46; Bizer Dzhambazov, 42; Katrin Ivanova, 32; Ivan Stoyanov, 32; and Vanya Gaberova, 29.

Roussev, Dzhambazov and Ivanova are also charged with possession of false identity documents with improper intention under section 4 of the Identity Documents Act 2010.