Bereznik was an European nation that existed in the 2060s.
In early 2065, the British government were forced to deny all knowledge of Lady Penelope Creighton-Ward's presence in Bereznik, stating she was in no way affiliated with them (COMIC: Duel of the Daleks) after she was arrested by the Bereznik Army on suspicion of murdering Tobolsk, the head of the Bereznik Secret Police. (PROSE: Zodiac's Rescue Bid!) The Bereznik government subsequently declared Penelope a renegade and offered a reward of 100,000 crownins, £20,000, for her capture, dead or alive. (COMIC: Duel of the Daleks) Later, an English woman believed to be Lady Penelope led an attack on the Bereznik castle prison of Kirov that was thought by TV 21 to be either a general revolt or an attempt to force the release of Professor Laryak. (PROSE: Fireball Mystery Flight!)
Shortly after her return from Bereznik, Lady Penelope made a sudden departure for Unity City to investigate the assassination of the Astran Kaplan. (PROSE: Kaplan Assassinated!)
In 2066, Admiral Beatty was arrested for passing secret information to Bereznik. His trial was scheduled for 26 February at the Unity City Espionage Court. (COMIC: The Archives of Phryne)
Later in the year, the Bereznik Secret Service plotted to assassinate the World Government Defence Minister while he was visiting the French President in Paris. Hermutt Clinger was selected as the assassin but the plan was ultimately foiled thanks to the efforts of Lady Penelope, Parker and Roger Lyon. Clinger managed to transmit a photograph of Penelope to Bereznik for identification, as well as seriously injuring her, but was himself fatally shot by Roger. Upon tracing Penelope's location to the Reinstat Clinic, the Chief of the Service ordered his aide to travel from Bereznik to the Clinic to confirm the news of her death. He did this to his satisfication, though he was purposely misled by the (alive and well) trio of special agents, resulting in the aide reporting back to the Chief who closed the file by marking the unknown woman deceased with a stamp. (COMIC: The Assassination Threat)
The British Secret Service recruited Lady Penelope to corroborate their suspicions and acquire proof actor Paul Carson was a Bereznik spy because she had been offered a role in a film alongside him. She found that his scripts contained specially-printed coded messages about an aerial car and a meeting in the desert. Colonel Thomas confirmed that the boss of the typing company Film Print Limited was a known Bereznik agent and that the aerial car referred to a piece of technology being devoloped at a World Government research plant in the Borrego Desert. Sometime later, Lady Penelope and Parker observed Carson receiving the plans to the car from a security guard at the facility from behind a sand dune. Carson was subsequently alerted to their presence and tried to pursue them to protect his secret but was ultimately killed in a car crash on the winding roads of the high hills. (COMIC: Desert Drama)
In 2069, Thunderbird 1 and Thunderbird 2 intercepted the Fireflash Mk II and forced it down just inside the Bereznik border after following a signal from a tracking device in Jeff Tracy's luggage. However, it was believed the hijacker had arranged a rendezvous at the border and so the Fireflash itself soon became "a fortress heavily defended by machine gun fire". The demands of the hijackers, who were in cahoots with the Hood, were for all four Thunderbird craft plus their designer and fifty billion dollars. If these specifications were not met it was suspected they planned to deliberately explode the atomic reactor of the Fireflash. (PROSE: Stalemate!)
It was incorrect to claim that Bereznik was a planet in the Solar System. (PROSE: Agents' Merit Award Test 3)