London's National Gallery is to limit visitor numbers to a major exhibition of Leonardo da Vinci works in an attempt to prevent large crowds detracting from the viewing experience.

Admissions will be fixed at 180 every half hour - 50 fewer people than the gallery is legally allowed to let in.

"We've looked hard at the problems caused by very popular exhibitions... and decided to take action," gallery director Nicholas Penny told The Times.

Advance booking opens on Tuesday.

In a statement, the gallery said it expected there to be "unprecedented demand" for tickets and advised patrons to book in advance.

Its decision to reduce the number of admissions, it added, had been "in response to visitors' comments regarding overcrowding in exhibitions".

Longer opening hours and the decision to open the exhibition on 1 January 2012 will add 20% to normal capacity, it said....