The National Gallery has banned visitors from taking in liquids after activist attacks on its collection.

       Just Stop Oil activists have vandalised paintings including works by Constable and Van Gogh, throwing orange paint and soup on the artworks and then glueing themselves to picture frames.

       The National Gallery said the ban on liquids being brought in had been introduced to limit future damage to the publicly-owned collection.

       It said: “Following recent incidents within the gallery, it is now necessary to introduce increased security measures to ensure the safety of all those who visit, National Gallery staff and the nation’s collection of paintings.

       “Free access to the National Gallery allows everyone to be inspired by humanity’s greatest achievements. The collection we hold is irreplaceable and, with each attack, we have been forced to consider putting more barriers between the people and their artworks to preserve these fragile objects for future generations.

       “Unfortunately, we have now reached a point where we have been forced to act to protect our visitors, staff and collection.”

       Since July 2022, the gallery’s collection has been targeted on five occasions. Just Stop Oil activists vandalised Van Gogh’s Sunflowers, Velazquez’s Rokeby Venus and Constable’s The Hay Wain.

       Pro-Palestinian activists from the group Youth Demand pasted over Picasso’s Motherhood in October in protest at the sale of arms to Israel.

       From this Friday, no liquids will be permitted in the gallery except for baby formula, expressed milk and prescription medicines. It has warned that the ban is likely to lead to delays for visitors, who will have to go through more thorough bag checks.