Italian Foreign Minister Massimo d'Alema will raise the case of former KGB spy Alexander Litvinenko when he travels to Moscow on Tuesday.
Talking Monday in Belgrade, where he is on a visit, D'Alema said he would ask the Russian authorities for "full cooperation" in a case which has "raised many questions which need to be cleared up".
Litvinenko died in London last month after being exposed to a radioactive substance called polonium 210.
An Italian who was in touch with him, Mario Scaramella, is in hospital in London after the same substance was found in his body.
British police are travelling to Moscow this week as part of their investigation into Litvinenko's death.
Scaramella, a consultant for a now-defunct Italian commission into Soviet-era spying, was one of the last people to see Litvinenko before he became ill.
On his death bed, the former KBG colonel accused Russian President Vladimir Putin of his death.
Moscow has dismissed the charge but has said it will work fully with investigations.
Russian Foreign Minister Serghei Levrov said Tuesday that the Litvinenko case must not be "politicised".
Scaramella, a security consultant, is under investigation in Italy for breach of secrecy rules and alleged arms trafficking.
After the news of Scaramella's hospitalisation, his recent movements have led to concern in Italy.
There was a brief scare at the Ischia court house on Tuesday.
Among his many activities, Scaramella is an honorary judge on the island.
