Novichok poisoning victim
Charlie Rowley has said he "didn't really get any answers" after meeting Russia's ambassador in
London.
The 45-year-old's partner,
Dawn Sturgess, died after being exposed to the nerve agent used to attack ex-spy
Sergei Skripal and his daughter
Yulia Skripal.
Mr Rowley visited the
Russian Embassy after the Sunday Mirror arranged the meeting with
Alexander Yakovenko.
But he said the diplomat told him Russia was not behind the attack.
Mr Skripal and his daughter Yulia were found seriously ill on a bench in Salisbury, Wiltshire, last March but survived.
It was months later when Mr Rowley and Ms Sturgess, 44, fell sick in nearby Amesbury, having come into contact with a perfume bottle believed to have been used in the poisonings.
Ms Sturgess died in hospital in July.
"I went along to ask them 'Why did your country kill my girlfriend?', but I didn't really get any answers," Mr Rowley told the Sunday Mirror.
Mr Yakovenko had seemed "genuinely concerned" during the 90-minute meeting, Mr Rowley said.
However, he added that the ambassador fed him "propaganda" and told him Russian-made Novichok would have been more powerful, killing more people.
"Some of what he said trying to justify Russia not being responsible was ridiculous," he told the paper.
In September, Scotland Yard and the Crown Prosecution Service said there was sufficient evidence to charge two Russians - known as Alexander Petrov and Ruslan Boshirov - with offences including conspiracy to murder.
They are accused of being members of the Russian military intelligence service the GRU.
Russia has repeatedly denied any involvement, with president Vladimir Putin claiming the two suspects were civilians.
During an interview, the pair said they were tourists.
The Sunday Mirror quoted Mr Yakovenko saying he and Mr Rowley were "on the same page" and wanted to see a report into the investigation published.
"I've seen a normal person who has really suffered a lot and who has suffered a tragedy in his life. If he asked for it, I would give him support," he reportedly said.