* Not clear when attack was to have taken place
* Vatican says trip unchanged
* First substantial protest of trip to Britain
(Recasts with arrests during papal visit, Vatican statement)
By Philip Pullella and Matt Falloon
LONDON, Sept 17 (Reuters) - Pope Benedict's security was in
the spotlight on Friday after London police arrested five men on
suspicion of preparing an attack in Britain.
It was not clear if the planned attack was related to the
pope's visit or when it was to have taken place, but it prompted
police to take another look at security for the pontiff, who was
on the second day of his visit to Britain.
The Vatican said the trip would go on unchanged. Police said
they had reviewed their arrangements for the visit and concluded
that their plan "remains appropriate".
The arrests were made by anti-terrorism police, who were
searching a business in central London and homes in the north
and east of the city but had not uncovered dangerous materials.
The five men, aged between 26 and 50, who were not named,
were arrested around 5:45 a.m. (0445 GMT), police said in a
The Pope has been heavily protected during his four-day
visit to Britain, travelling in a custom-built bulletproof car
surrounded by security officials.
Four young British Islamists killed 52 people and wounded
hundreds when they set off suicide bombs on three underground
trains and a bus on in July 2005.
The Vatican was told of the arrests as the pope was arriving
at a Catholic university in southwest London.
"We are totally confident in police and there are no plans
to change the programme," said Father Federico Lombardi. He said
the pope was calm and looking forward to the rest of the visit.
At the university, Benedict reminded his church, reeling
from evidence of widespread sexual abuse of children by priests,
that its first priority was to provide a safe environment for
"Our responsibility towards those entrusted to us for their
Christian formation demands nothing less," he told a gathering
of Catholic schoolteachers and administrators.
In the first substantial protest of his delicate visit to
Britain, several hundred people whistled and shouted "Pope must
resign!" and "Shame!" as the papal motorcade entered a nearby
Catholic school complex.
They held placards reading "Hypocrisy and lies" and
"Catholic paedophile cover up".
The sex abuse scandal, in which priests who abused children
were moved from parish to parish instead of turned over to
police, has hounded Benedict's five-year-old papacy, even though
most of the abuse took place decades ago.
On Thursday, the pope told reporters aboard the plane from
Rome that he was shocked by what he called a "perversion" of the
priesthood and acknowledged that the Church had not been
sufficiently vigilant and decisive in dealing with the scandal.
(additional reporting by Avril Ormsby and Maria Golovnina;
Editing by Kevin Liffey)
(For more on faith and ethics, see the Reuters religion blog
FaithWorld at http://blogs.reuters.com/faithworld)
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