ROME - The shooting outside the Italian prime minister's office on Sunday could not be described as terrorism although the bitter political climate of the past few months has increased tensions, the mayor of Rome, Gianni Alemanno said.

"It's not an act of terrorism but certainly the climate of the past few months has not helped," Alemanno told reporters.

A man was arrested after the shooting in which two police officers and a passerby were wounded just as the new government of Prime Minister Enrico Letta was being sworn in at the presidential palace around a kilometre (mile) away.