A secretary was slightly injured when a letter bomb exploded and caught fire at the offices of a senior British MEP.
Gary Titley was not at the office at the time
It was addressed to Gary Titley, leader of the UK Labour members and was
opened by a secretary in his office in Radcliffe, Greater Manchester, on Monday.
It was the third confirmed device targeting Euro-MPs, and the first known to
have been sent to the UK.
Italian anarchists in Bologna are believed to be behind the campaign.
At least two other letter bombs were sent to European Parliament headquarters
in Brussels - addressed to German and Spanish political leaders.
All three were very similar, concealed in books in brown envelopes.
Mr Titley, who was travelling to Brussels at the time, said: "There can be no justification for these attacks which in reality are an
attack on democracy.
"There's suggestions this has come from an Italian
"Quite why they've targeted non-Italian politicians is not yet clear. But I
understand leaders of the main political parties have received these devices.
'Got under defences'
"Mine coming through the constituency office meant there wasn't any
screening, as there is here in the European Parliament."
He said the device was the last item of mail to be dealt with from the backlog of post which had arrived during the Christmas holidays.
When the package started to give off black smoke, the secretary threw it aside and it burst into flames, he said.
The office manager put out the fire.
Mr Titley said: "Today being the first day back after the holidays, so much mail, everyone feeling very relaxed, obviously this one got under our defences."
Greater Manchester Police said: "Mr Titley's secretary opened the package and it exploded like a party
popper, giving her slight injuries to her hand."
Monday's letter bombs were all posted on 22 December in Bologna, the departure point for earlier letter bombs to senior EU officials including Romano Prodi.
The group claiming to be behind the attacks calls itself the Informal
Anarchist Federation and is protesting about what it calls the "repressive apparatus of control" in Europe.
The latest packages to turn up in Brussels appear to have passed through
European Parliament security screening operations before the earlier devices
alerted staff to a Bologna-based threat.
Thousands of packages
They were then despatched to the offices of the relevant MEPs where they
remained during the fortnight-long Christmas break.
One, which was opened by a staff member, was addressed to the leader of the
centre-right European People's Party, Hans-Gert Poettering.
Another unopened, device was sent to the head of the Spanish Conservatives, Jose Ignacio Salafranca.
Previous letter bombs were sent to European Commission President Romano Prodi
at his Bologna home, to the head of the European Central Bank in Frankfurt,
Jean-Claude Trichet, and to the offices of Eurpol, an EU police data-gathering
centre in the Hague.
European Parliament spokesman David Harley said a security review was under
"The Belgian police are now working with our security services to re-scan the
tens of thousands of packages which have been sent to the European Parliament in
recent weeks," he said.