Europe's institutions are coming under letter bomb attack by groups of Italian anarchists, according to police. In the latest incident, several letter bombs turned up at the European Parliament on Monday, one addressed to the leader of Europe's conservative Popular Party, Hans Gert Poettering. It comes after a spate of letter bomb attacks on European institutions last month. This device exploded, starting a small fire, but injured no-one. Another also exploded in the office of a British MEP. Eyes are now turning to the parliament's post room, as all Monday's letters were postmarked December 22 and were sent from Bologna in Italy. As MEPs have been on holiday, their postbags are full to bursting and there are fears there could be more bombs in the unopened mail. On December 27 EU commission head Romano Prodi got a bomb in the post. Devices have also been sent to the heads of Europol and Eurojust, and the boss of the European Central Bank. The devices have been designed to disrupt rather than destroy, but are raising questions about the EU's institutional security. **PHOTO CAPTION*** European People's Party leader Hans-Gert Poettering. (AFP/File)