The prime minister’s special representative for Pope Benedict’s visit to the UK says protesters should show restraint.

Chris Patten, a former governor of Hong Kong and Tory minister, urged critics of the Pope to show tolerance.

The Pope is due to visit the UK for four days in September and gay and secular groups have already said they will hold demonstrations to protest the trip.

Pope Benedict has repeatedly attacked homosexuality and gay marriage in the last few years, along with equality laws, abortion, contraception and the use of condoms to fight HIV.

Mr Patten, who was appointed by David Cameron to help coordinate the visit, told Reuters: “I hope that (the protests) will be done with restraint, and that it will be done with a show of tolerance.

“It would be an extraordinary irony if those who polemicise past intolerance by churches are to become themselves the proponents of intolerance towards churches.”

Speaking yesterday, he added that the public cost of the visit was likely to rise by up to 50 per cent to £10-12 million, excluding security.

The Catholic Church is expected to have to pay out more than £7 million, although the Spectator reported last month that Catholic archbishops of England and Wales were told at a private meeting that costs had risen to nearer £14 million.

The church was left heavily in debt after the last papal visit, that of Jean Paul in 1982.

However, the National Secular Society believes that the true cost of the visit could be closed to £100 million due to the Pope’s security.

The organisation came to the figure by researching the cost of papal visits in other countries.

NSS president Terry Sanderson said: “We predicted this would happen at the very beginning, although the previous government denied it.

“But this is only the start. Strathclyde Police are expected to protect the Pope in Scotland and the West Midlands Police in Birmingham. They are reeling from the news that they will have to find tens of millions of pounds for security costs from their already stretched budgets.”

When the event was first announced, the NSS gathered a petition of 28,000 names protesting at the state funding of the visit and a coalition called Protest the Pope was formed.

In an end-of year address in 2008, the Pope said that the existence of gay people threatens humanity as much as the destruction of the rainforests does and that “blurring” genders through acceptance of transgender people would kill off the human race.

He has also attacked the use of condoms to tackle HIV, saying they may make the problem worse.