'The Morning Walk' suffered two long scratches and has been removed from the gallery

The National Gallery was thrown into panic when a visitor attacked one of the paintings with a screwdriver.

'The Morning Walk', a 1785 portrait by Thomas Gainsborough, suffered two long scratches that penetrated the paint layers.

Gallery assistants quickly rushed to detain the man, with members of the public helping to restrain him.

Unconfirmed reports claim that the man said he had a bomb.

A Metropolitan police spokesman said: 'Police were called at approximately 14.10 hours on Saturday, 18 March to reports of a painting damaged at the National Gallery on Trafalgar Square.

'A man has been arrested on suspicion of criminal damage. He was taken to a central London police station where he remains in custody.'

Keith Gregory, 63, of no fixed address, was later charged with causing criminal damage to the painting on Sunday.

He has been remanded in custody and will appear at Westminster Magistrates' Court on Monday.

The painting was removed from display. National Gallery conservators are now assessing the level of damage.

The painting (top right) sits in the National Gallery's iconic Room 34, which featured in the James Bond film Skyfall

The East Wing of the National Gallery had to be evacuated and was closed for two hours after the incident.

'The Morning Walk', which sold for £30,000 in 1954, sits directly opposite 'The Fighting Temeraire' by Joseph Turner - made famous for its appearance in the James Bond movie 'Skyfall'.

The painting, also known as 'Mr and Mrs William Hallett', features a young couple on a woodland stroll with an attentive dog at woman's heel. At the time portraits of wealthy couples in a natural setting were a popular status symbol.

The East Wing of the National Gallery (pictured) had to be evacuated for two hours

Thomas Gainsborough was one of the leading portrait painters in England in the 18th century - and a founding member of the Royal Academy.

Some of his paintings have sold for up to £6.5 million pounds.