Italian police found a map detailing central London earlier this week when they arrested five Moroccans in a building containing 2.2 pounds of explosives, news reports said Friday.
Authorities were questioning the suspects and were not available to confirm the reports. Police earlier acknowledged that the raid and arrests near the northern city of Rovigo on Wednesday uncovered maps and explosives, but would not give details.
In London, British Prime Minister Tony Blair's spokesman welcomed the arrests but refused to comment on the reports. The Home Office only said it was in close contact with Italian authorities, providing no details.
The five Moroccan men were arrested after a routine search for illegal immigrants turned up explosives and maps, authorities said Thursday. The Italian news agency ANSA also reported that authorities were believed to have found the addresses and plans of NATO bases in Italy.
The suspects included a religious leader of Rovigo's Muslim community, Reduane Bnoughazi, 32, and four other men aged 28-41, police say.
They are all charged with possessing explosives.
Their lawyer, Sofia Tiengo, said the men deny all the charges. She said the explosives were found in an abandoned building where some of the suspects had been squatting, but that the material didn't belong to the five men.
U.S. Attorney General John Ashcroft and Justice Minister Roberto Castelli, who met in Rome on Thursday, described the arrests as part of Italy's fight against terror.
Dozens of people have been detained as part of a probe into militant Islamic cells operating in Italy, which prosecutors say provided logistical and other help to Usama bin Laden's Al Qaeda operatives.
British anti-terrorist police have staged several raids after finding traces of the deadly poison ricin in a London apartment on Jan. 5. Five men have been charged with chemical weapons offenses in connection with the ricin.