Italian police say they have arrested two people suspected of being behind a Twitter account that carried threats in the name of the Islamic State group against some of the country's most famed monuments.

Police on Wednesday said they had arrested a Tunisian and a Pakistani on suspicion of terror association and subversion. Police said the two are Islamic State backers and used social networks to threaten violence.

They said the threats in the name of Islamic State carried on the Twitter account "Islamic — State in Rom" featured images of the Roman Colosseum and Milan's Duomo cathedral, with a warning that they were identifying targets and preparing to strike.

The suspects were arrested in the northern city of Brescia and searches were being carried out throughout the Lombardy region.