Bulgarian officials say they will investigate reports about a third suspect in last year's nerve agent poisoning of a Russian former spy in Salisbury.
The man linked to the poisoning of Sergei Skripal and his daughter Yulia, has also allegedly been involved in a 2015 poisoning in Bulgaria.
Tsvetan Tsvetanov of the ruling GERB party told the TV channel on Sunday that Bulgaria's intelligence services will present evidence at a hearing soon before the parliamentary committee on homeland security.
The hearing follows a report by the investigative group Bellingcat, which says an alleged Russian GRU military intelligence agent arrived in Bulgaria in April 2015, just a few days before Bulgarian businessman Emilian Gebrev was poisoned by an unidentified substance.
Mr Gebrev, a key executive in the country's arms industry, survived the attack, but authorities still do not know who poisoned him.
Bellingcat said on its website that the 45-year-old agent, who travelled under the alias Sergei Vyacheslavovich Fedotov, had been "conclusively identified as an agent of Russian military intelligence", or GRU.
Bellingcat said Fedotov is also suspected of being involved in the Novichok nerve-agent poisoning of Mr Skripal in March 2018, having arrived in Britain two days before the attack.
Both Skripals survived but spent weeks in the hospital and are now at an undisclosed location for their own safety.
British officials have blamed the attack on the GRU, and charged two Russian suspects, who travelled under the names Alexander Petrov and Ruslan Boshirov. The men, and Russian authorities, deny involvement in the poisoning, and Moscow refuses to extradite them to Britain.
The Skripal poisonings set off a wave of recriminations between Britain and Moscow, prompting dozens of envoys to be expelled.
Mr Tsvetanov, a former Bulgarian interior minister, said that the new probe was being co-ordinated with foreign partners.
"I am certain that the necessary co-ordination has already been set up between the Bulgarian, British and European authorities on the case and they are working actively on it," he told reporters.