Two suspected letter bombs have been sent to the European police body Europol and European Central Bank head Jean-Claude Trichet, officials say.
A suspected bomb sent to Trichet was found in the ECB's post room
Bomb experts on Monday defused a bomb in a package sent to the Europol headquarters at The Hague.
Hours earlier police in Frankfurt, Germany found a possible parcel bomb that had been sent to Mr Trichet.
On Sunday European Commission head Romano Prodi escaped unharmed when a parcel bomb exploded at his home.
An anarchist group said it was behind two other explosions in rubbish bins near Mr Prodi's home in the past week.
Staff at Europol headquarters notified police after a package was scanned and found to be "suspicious", Europol officials told French news agency AFP.
EC chief Romano Prodi narrowly escaped a bomb attack on Sunday
A bomb squad was sent to the offices and the bomb was defused. Police would not say how large the device was.
Europol is the EU's law enforcement organisation, which handles criminal intelligence and assists authorities in EU states in their fight against organised crime.
Hours earlier police in Frankfurt, Germany said they had intercepted a suspected parcel bomb sent to European Central Bank President Jean-Claude Trichet.
The suspected bomb was discovered in the post room of the bank's offices early on Monday morning, a spokesman told Reuters news agency.
It had been sent from the northern Italian town of Bologna, where European Commission President Romano Prodi narrowly escaped unhurt after a parcel bomb attack on his home.
Mr Prodi said the package he received at home contained a book wrapped in yellow paper and addressed to his wife, which been cut to insert explosive powder.
The book used was The Pleasure by Gabriele D'Annunzio, a famous early supporter of Fascism before his death in 1938.
Mr Prodi joked that the choice of book might have been ironic.
A previously unknown group known as the Informal Anarchic Federation claimed responsibility for two earlier rubbish bin attacks near Mr Prodi's home in which no-one was hurt.
In a letter to an Italian newspaper the group said it wanted to target "the apparatus of control that is repressive and leading the democratic show that is the new European order".