LONDON — Three Bulgarian nationals suspected of spying for Russia while living in Britain have been arrested and charged following a major national security investigation, the Metropolitan Police said Tuesday.

The police said in a statement that five people, three men and two women, were arrested under the Official Secrets Act by counterterrorism detectives in February. Police confirmed the investigation relates to Russia.

Police also charged three of them under the Identity Documents Act with possessing "false identity documents with improper intention."

Authorities did not specify what the alleged fake documents were, but the BBC, which first reported the story, said that the people were working for Russian security services and they had passports, identity cards and other documents for Britain, Bulgaria, France, Italy, Spain, Croatia, Slovenia, Greece and the Czech Republic.

The police identified the three people as Orlin Roussev, 45, Bizer Dzhambazov, 41, and Katrin Ivanova, 31. Dzhambazov and Ivanova share the same address.

Roussev's LinkedIn profile says that he once worked as a strategic adviser to the Bulgarian Ministry of Energy and that his most recent work was as owner of NewGenTech, a company involved in artificial intelligence and signals intelligence.

Ivanova worked as a medical laboratory assistant, according to her LinkedIn profile, and Dzhambazov's profession was described by the BBC as a driver for hospitals.

The BBC said that the trio, who have not entered pleas to the charges, are set to stand trial at London's Old Bailey court in January.

Britain is no stranger to high-profile incidents involving Russian intelligence operations. In 2018, former Russian double-agent Sergei Skripal and his daughter Yulia were poisoned by a military-grade nerve agent in Salisbury. The British government said it was "highly likely" that Moscow was behind the attack.

In 2006, Alexander Litvinenko, a former Russian-intelligence officer, died in London after drinking tea laced with poison. British authorities pointed the finger at two former KGB officers.