The Vatican will rent out the Sistine Chapel for a private concert for the first time in history, with the proceeds going to charity.

The choral performance this weekend will be attended by 40 tourists who signed up for a five-day, 5,000 euro per person tour of Italy, hosted by Porsche.

News of the event came as the Vatican also announced a plan to restrict the number of visitors to the historic chapel to 6 million a year, to protect the delicate frescoes inside from damage caused by tourists.

Visitors to the chapel can reach 20,000 a day in summer, with up to 2,000 people inside at a time.

Dust brought in from outside, body sweat and carbon dioxide pose a major risk to the chapel's famous ceiling frescoes, painted by Michelangelo over 500 years ago.

They include one of the most famous scenes in the history of art - the arm of a gentle bearded God reaching out to give life to Adam.

To protect the work of the Renaissance master, the Vatican has installed a new climate control system that will filter the air in the chapel, as well as a new high-tech lighting system that will cut damaging heat by more than half.

"I am convinced that the Vatican Museums, in particular the Sistine Chapel, have reached the maximum number of visitors possible," Vatican Museums head Antonio Paolucci said.

Mr Paolucci said the current number of 6 million visitors a year would be the maximum tolerated.

"We did not do all this in order to allow more people into the Sistine Chapel," he said.

Work on the new systems began in June and are expected to be in place by the end of this month.

Michelangelo's frescoes, inaugurated in October 1512 by Pope Julius II, underwent a major 14-year restoration that ended in 1994.

They also include the famous Last Judgement on the wall behind the altar, which the artist painted separately in 1535 and 1541.

In recent years art historians and restorers have called for severe limits on the number of tourists allowed to enter the chapel, part of the vast Vatican Museums complex.

Mr Paolucci said the current system - a mix of reservations made through the internet or travel agencies and queuing up outside - would continue for the time being, but did not exclude the possibility of switching to a reservations-only system.

Apart from the potential damage to the frescoes, critics have also said the number of people allowed into the chapel should be reduced because it is a place of worship.

But Mr Paolucci appeared to rule this out.

"We all would like the Sistine Chapel miraculously empty ... but we live in the democracy of consumption," he said.

BBC/Reuters