Security has been increased at various "sensitive" locations in Rome in the wake of the Boston marathon explosions which killed three people and injured more than 100 on 15 April.

The American embassy, consulate and residence of the American ambassador, as well as the campuses of US universities in the capital have tightened their security arrangements, on the orders of Rome's police commissioner.

The city’s Fiumicino international airport has also stepped up its security checks, with special attention being paid to passengers on American or Israeli flights.

In a message to US president Barack Obama, the outgoing Italian premier Mario Monti pledged Rome's support for the American people, describing the bombings as a "cowardly act of violence that provokes scorn."

The Italian president Giorgio Napolitano expressed his "deepest solidarity and disdain" while Pope Francis sent a message of condolence for the victims – via Boston archbishop Seán Patrick O'Malley – saying he was "deeply pained" by the "senseless tragedy".