A bomb was defused overnight near the Sardinian holiday villa of Prime Minister Silvio Berlusconi hours after a visit by the British prime minister Mr Tony Blair, Italian police have said.
A local anarchist group issued a warning and claimed responsibility for planting the bomb, which police described as a low-impact, home-made device.
Security was stepped up around the prime minister's villa, but Berlusconi 's office said his holiday schedule was unchanged despite the threat.
"There have been no alterations. He is calm and remaining in Sardinia," his press office said.
A caller claiming to be from the Proletarian Nuclei for Communism (NPC), a radical group active on the island, phoned the Sardinian newspaper L'Unione Sarda at 10:45 p.m. on Tuesday warning of two bombs.
The caller said one had been planted in a large bin near the centre of the tourist town Portorotondo, a couple of kilometres (about a mile) from Berlusconi 's sprawling Villa Certosa.
"The other one - we're not telling you, go and find it. It's for Berlusconi ," the voice said, according to a report in the national daily Corriere della Sera.
Police discovered the bomb in the bin and defused it soon after the warning. Corrieresaid it had been set to go off at 2 a.m.
After hours of searches, police said on Wednesday they had concluded there was no second bomb.
"But security measures around sensitive sites have been intensified," a police spokesman in Sardinia said.
Mr Blair and his wife Cherie left Sardinia a few hours earlier after a brief stay at Berlusconi 's luxury retreat.
Officials said the NPC was an "anarcho-separatist" group responsible for about 20 attacks over the last four years, including small bombings of government party headquarters and labour union offices in Sardinia.
Italy is under a heightened state of alert following threats from Islamist groups to attack the country and its premier because of the presence of Italian troops in Iraq.
The country is also home to numerous domestic radical groups which occasionally use bombs to forward their aims.