Italian police have arrested two alleged Islamic State (Isis) sympathisers who boasted of future attacks in the Mediterranean country by posting photos of some of its most iconic sights on social media.

The pair, a Tunisian and a Pakistani, also planned attacks against a military base near the northern Italian city of Brescia, said prosecutor Maurizio Romanelli.

The Ghedi Air Force Base also houses the US 704th Munitions Support Squadron.

The two men are suspected of being behind the Twitter account "Islamic_State in Rom[e]" that published a series of threatening posts, earlier this year.

These consisted of various mobile phone pictures depicting numerous monuments, including the colosseum in Rome and Milan's Duomo cathedral, in the background of a handwritten message on a piece of paper bearing the IS symbol and reading "We are in your streets".

The postings made international headlines in Spring, after they were reported by SITE, an intelligence group monitoring jihadi activity online.

"We are everywhere, we are choosing targets waiting for the X-hour," read other messages written in Italian, Arabic, and French.

The two suspected would-be jihadists, both males, regularly lived and worked as labourers in the construction and cleaning sector near the industrial town of Brescia, northern Italy. They are facing charges of terror association and subversion.

Interior Minister Angelino Alfano tweeted his satisfaction at the police operation, writing: "our control system has once again shown its efficiency".

Italy often features in IS propaganda threats as according to the group's Islamist rhetoric, all Westerners are offspring of the cradle of Christianity, Rome, which hosts the Vatican.

Meanwhile in Spain, police arrested an alleged IS recruiter who operated from the north African enclave of Melilla.