The Vatican, overwhelmed by the growing number of visitors crowding into the Sistine Chapel, is attempting to reduce queues by cutting back opening hours for visitors in favour of tour groups that book in advance.

The Vatican Museums are marking 500 years as one of the “must see” sights of Rome. Visitors have doubled over the past ten years, with sometimes as many as 10,000 a day.

The Sistine Chapel, Raphael Rooms, map gallery, Borgia Apartments and Egyptian and Etruscan collections are packed with treasures. A celebrated 1st-century marble statue of the Trojan priest Laocoon struggling with snakes is on special display to mark the museums’ anniversary.

However, the queue to get in often stretches up to six deep for a mile round the Vatican’s medieval walls, with a wait of two hours or more. The numbers in the Sistine Chapel increasingly risk damaging the frescoes by Michelangelo, restored in 1994.

Addressing museum staff in November, Pope Benedict XVI said that the number of visitors had reached four million a year. Although many of them were “not Catholic, not Christian and perhaps not even believers”, the Vatican’s collection of masterpieces “leads the mind to open itself to the sublime” and so highlights “the continuous interweaving between faith and art, the divine and the human”, he said.

Francesco Riccardi, a senior museums administrator, told The Times: “Our intention is to optimise visits while reducing the long queues.” The galleries were created as the Pope’s private collection during the Renaissance and were never meant for public viewing.

From Monday the entry fee for individual visitors, who will not be able to enter before 10am, goes up from €12 (£8) to €13. Earlier slots from 8am will be reserved for groups booked 30 days in advance through tourist agencies that lodge a deposit of €6,000 with the Vatican. The museums remain open until 1pm in winter and 4.45pm in summer.

But the move is not without critics. John Fort, author of the updated version of The Companion Guide to Rome, said that the new system would not solve anything. “I do not believe people will be discouraged from queueing — all that will happen is that they will feel frustrated because they are paying more for less time.

“The problem is exacerbated by coachloads of passengers from cruise ships which dock at Civitavecchia and offer day trips to Rome,” Mr Fort said. “I sometimes wonder if it wouldn’t be better to build replicas of the Colosseum or the Sistine Chapel outside Rome instead.”

He added that the real problem was “the exponential increase in the number of tourists to Rome”. Walter Veltroni, the Mayor of Rome, recently announced that 18 million tourists visited the capital last year and he forecast a rise to 20 million this year.

In the Sistine Chapel Clive Burgess, from Grays, Essex, said that shortening the opening hours was not the answer. “There is not nearly enough time to see everything as it is,” he said as he gazed at Michelangelo’s Last Judgment while museum guards sought to move visitors on and shouted for quiet amid the hubbub.

To offset any drop in income through the shorter hours the Vatican is increasing charges for “special tours” in the afternoon, after the museums close to the general public. Groups of up to 30 people, who at present pay €1,800 for the privilege of having the museums to themselves, will pay €2,500, while for groups of 400 people the price almost triples, from €7,000 to €20,000.