Foreign Minister Franco Frattini said the attacks represented "a serious threat" against foreign embassies, while Chile's ambassador Oscar Godoy Arcaya condemned "an absolutely irrational and brutal act of terrorism."

Police said checks were under way in all the embassies in the Italian capital and the city's mayor said emergency services were on the ready.

"This is a wave of terrorism against the embassies. It's more worrying than a single attack," the mayor, Gianni Alemanno, told reporters.

"International lines of inquiry are being followed," Alemanno said.

Interior Minister Roberto Maroni said investigators were following a possible anarchist link behind the attacks "following analogous incidents that happened in November in Greece."

AFP