Pope's UK visit 'could cost taxpayers £12m'
The cost to taxpayers of the Pope's visit to Britain could rise to £12m - up to £4m higher than previous figures, the government has said.
That bill for the September trip does not include policing costs for the government, Lord Patten said.
The main event, a mass to beatify Cardinal John Henry Newman, has been moved from Coventry airport to a smaller venue outside Birmingham.
The Pope will visit Edinburgh, London and Glasgow during the four-day trip.
The trip will also cost the Catholic church £7m - a figure which could also rise.
This will be the first official Papal visit to the UK. Pope John Paul II made a purely pastoral visit in 1982, but Pope Benedict XVI's trip will combine both pastoral events and formal state business.
The visit has, however, caused controversy in the UK because of the cost and the scandal surrounding child abuse within the Catholic Church.
At a news conference on Monday, Archbishop of Westminster Vincent Nichols said it should be up to the Vatican to decide whether the Pope should meet some of those who had suffered abuse at the hands of Catholic clergy.
"It's easy for people to call for some great public gesture, such as meeting victims, but that in itself is a very difficult process for someone who has suffered abuse," he said. "And we must not use those who have suffered abuse for some kind of public agenda.
"So I think these are very difficult issues, but the visit will not be centred on them.
"It will be a unique historical moment in the life of this country."
Special representative Lord Patten said previous assessments of non-policing costs had underestimated the "complexity and sophistication" of the visit and the government would have "to make a larger commitment".
Asked about the current financial climate, Lord Patten said: "I think this country has to learn to live within its means... It does not mean that state visits and manifestations of the generosity of the state have to be distant memories."
The Catholic Church had planned to contribute £7m for the pastoral side of the visit, and Archbishop Nichols said so far about £1.1m had been gathered from parish collections and almost £4m from private donors and other sources.
But he said more would be needed, adding: "That will be a problem, but we will not be looking, as it were, to the state to support the expressions and the celebration of the Catholic faith."
The Pope is travelling to the UK at the invitation of the Queen, and she will meet him at Holyroodhouse in Edinburgh on 16 September, the first day of his trip.
He will travel along the city's Princes Street in the Popemobile before heading to Glasgow for a public Mass.
After that, he will move to London and will make a speech to representatives from the worlds of politics, culture and business at Westminster Hall.
An evening of prayer will also be held in London's Hyde Park, along with a public appearance on the Mall.
The beatification of Cardinal Newman, who died in 1890, will take place on 19 September at Cofton Park on the outskirts of Birmingham.
The Mass - which paves the way for the English cardinal to be officially named a saint - was originally planned to take place at a much larger venue at Coventry airport.
The BBC's religious affairs correspondent Robert Piggott said the church had denied the change was for reasons of cost.
Archbishop Nichols said he doubted the airport would have been able to cope with the sort of crowds that turned out for the last Papal visit in 1982.
"Getting 200,000 people in an airport in 2010 is quite different to the task in 1982," he said.
"As we all know, there is far more care taken about safety, about security, about health provision.
"But the reason is not that. The reason is because Cofton Park is very close to the place where Cardinal Newman lived during his summer months - it's a park around which he walked.
"It puts the ceremony of his beatification right in the context of his life, and I think it's that resonance, above all else, that we were looking for."