Six men have been arrested by the Metropolitan Police in London, suspected of preparing an attack against Pope Benedict who is on a state visit to Britain.
The arrests follow a warning Thursday night from the head of Britain's MI5 security service of a potential threat against the pope.
The five men, between the ages of 26 and 50, have been taken to a central London police station as officers were searching a business in central London and homes in the north and east of the city. None of the men have been charged.
It is not clear whether the investigations relate to a plot against the pope himself or an element of the visit.
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Vatican spokesman, Rev. Federico Lombardi, says the pope was informed and is not worried and remained calm. Lombardi says the Vatican has complete trust in the British police and does not consider the situation particularly dangerous.
The pope's visit has drawn criticism in the mostly Protestant, highly secular Britain. His trip is also overshadowed by the Catholic Church's clerical abuse scandal, as well as the Vatican's stance on gay rights, abortion and contraception.
Pope Benedict held a meeting with members of other religions Friday and stressed the need for dialogue and cooperation. He was speaking at Saint Mary's University College in Twickenham.
The pope said that as followers of different religious traditions working together for the good of the community, great importance is attached to this "side by side" dimension of cooperation, which complements the "face-to-face" aspect of continuing dialogue.
The pope said that in order for dialogue to be fruitful, it requires reciprocity by all those involved.
"I am thinking in particular of situations in some parts of the world, where cooperation and dialogue between religions calls for mutual respect, the freedom to practice one's own religion and to engage in acts of public worship, and the freedom to follow one's conscience without suffering ostracism or persecution, even after conversion from one religion to another," said Pope Benedict.
The pope added that when such respect and openness is established, people of different religions will work together effectively for peace and mutual understanding.
Earlier the pope met with thousands of cheering schoolchildren and students at the Saint Mary's University College's sports field, that has been inaugurated in honor of his predecessor Pope John Paul II and in view of the 2012 Olympic Games in London.
Young people cheered, sang and handed gifts to the pope. In an address to them, he urged them to ignore the temptations of the celebrity culture they live in. He said they should not be swayed by wealth and fame.
"Having money makes it possible to be generous and to do good in the world, but on its own it is not enough to make us happy," added Pope Benedict. "Being highly skilled in some activity or profession is good, but it will not satisfy us unless we aim for something greater still. It might make us famous but it will not make us happy."
The German pope was met by some 125,000 supporters at the start of his visit in Edinburgh, Scotland. Queen Elizabeth II officially welcomed the pontiff. This is only the second papal visit to Britain since the Church of England broke away in the 16th century. Pope Benedict is expected to conclude his trip with a beatification mass for 19th century cardinal John Henry Newman.