Police have arrested an Italian man who met Russian former spy Alexander Litvinenko the day he fell ill from poisoning, Italian news agencies said.
Mario Scaramella met Mr Litvinenko the day he fell ill
The two men met at a London sushi bar on 1 November. Mr Litvinenko died on 23 November from radiation poisoning.
Mario Scaramella is being investigated in Italy for arms trafficking and violating state secrets.
Scotland Yard said the arrest in Naples was not part of their investigation into Mr Litvinenko's death.
Mr Scaramella was arrested on his return from London.
The Italian had been in hospital in London, under observation after testing positive for the highly toxic isotope polonium-210, which is thought to be the cause of Mr Litvinenko's death.
However, Mr Scaramella did not develop any symptoms of illness.
On his deathbed, Mr Litvinenko blamed Russian President Vladimir Putin for involvement in his poisoning.
The Kremlin has dismissed suggestions it was involved in any way as "sheer nonsense".