A man suspected of rioting has been arrested after a mob gathered and smashed a window at an Indian high commissioner's office in London.

At around 1.50 pm on Sunday, Westminster's Aldwych building received a call for assistance from the Metropolitan Police, and two security guards received minor wounds.

Social media videos showed a man removing the Indian flag from the building's first-floor balcony as a group of people below waved yellow "Khalistan" banners to appear to support him. They are thought to be a part of a separatist Sikh movement that wants to find a new homeland or breakaway state.

An investigation into the incident has been opened by The Met. Windows at the high commission building were broken, according to a spokesperson. Two members of the security staff sustained injuries. These are thought to be minor, and no hospital treatment was necessary.

"Officers arrived at the scene. Before the police arrived, the majority of those present had left.

A male was detained nearby on suspicion of a violent disorder shortly after an investigation was launched. Investigations continue.

Sadiq Khan, the mayor of London, Lord Ahmad, the minister in charge of foreign affairs, and Alex Ellis, the British high commissioner to India, all condemned the incident on Twitter.

"I denounce the violent disorder and vandalism that occurred today at the Indian high commission," Khan said. This type of behaviour has no place in our city. The Met has opened an investigation into today's activities.

Am horrified by today's attack on the Indian high commission in London, Ahmad wrote. This behaviour is totally unacceptable and goes against the Mission and its employees' integrity. The security of the Indian high commission will always be a top priority for the UK government.

"I condemn the deplorable acts committed today against the people and property of the @HCI London - totally unacceptable," said Ellis.