A man has been arrested after 20 children were injured in an attack at a primary school in Beijing.

In a post on Chinese social media site Weibo, the Xicheng district government three of the 20 children suffered serious injuries – however, they are in a stable condition.

Posts on social media suggested some of the children had suffered knife wounds to the head.

All of the injured children are now in hospital.

The attacker was arrested at the scene and an investigation is now underway.

Chinese authorities did not say what kind of weapon was used in the attack.

China has suffered a series of knife attacks on school children in recent years.

Last October, 14 children were in an attack in the Banan district of Chongqing; a large city in the west of the country.