A man in his 70s has been stabbed at one of the largest mosques in the United Kingdom's capital, London.

The victim's life is not in danger, according to news reports.

The Metropolitan Police force said officers were called on Thursday to the London Central Mosque near Regent's Park. Officers found one man with stab wounds, and paramedics treated him at the scene before he was taken to hospital.

Police said a man was arrested at the scene on suspicion of attempted murder. On Twitter, mosque-goers posted images of a man being held down by police on the mosque floor.

Images posted on social media showed a white man in a red-hooded top, jeans and bare feet being pinned to the floor by police officers inside the mosque, as others, including a small child, watched on.

One video showed a knife on the floor under a plastic chair.

Witnesses said the victim was the meuzzin, the official who leads the call to prayer.

The attack comes less than 24 hours after a gunman, apparently motivated by far-right ideologies, killed nine people in Germany.