Security was beefed up around the Indian High Commission here on Monday and Scotland Yard detained one person in connection with vandalism at the mission by Khalistan supporters a day earlier as India asked the UK to quickly arrest and prosecute those involved in the attack.
The tricolour flying atop the Indian High Commission in London was grabbed at by the protesters waving separatist Khalistan flags and chanting pro-Khalistan slogans on Sunday.
After the incident, police arrested one person related to the violent disorder.
In New Delhi, Foreign Secretary Vinay Kwatra said on Monday that India has asked the UK to quickly arrest and prosecute those involved in pulling down the Indian flag at its mission in London.
Kwatra said that India lodged a strong protest and clearly indicated to the British authorities the need for putting up adequate security at the Indian high commission.
Following the incident, India summoned the senior-most British diplomat in Delhi and demanded an explanation over complete "absence of security" at the mission.
Kwatra, replying to a question at a media briefing, said the British deputy high commissioner was summoned and India demanded that the culprits and perpetrators of what happened in London on Sunday be quickly "arrested and prosecuted".
On Sunday, a group of pro-Khalistan protesters also attacked and damaged the Indian Consulate in San Francisco, prompting sharp condemnation from Indian-Americans who demanded immediate action against those responsible for it.
Kwatra, however, did not respond to a query on reports of pro-Khalistan protesters attacking the Indian Consulate in San Francisco.
In Canberra, Khalistan supporters gathered outside Australian parliament on Monday to protest against police crackdown on radical preacher Amritpal Singh and his associates in Punjab.
Officials from the mission in London said the "attempted but failed" attack had been foiled and that the tricolour was now flying "grander", with a larger tricolour now adorning the India House façade.
The Metropolitan Police said two members of security staff sustained minor injuries, which did not require hospital treatment and an investigation has been launched after an arrest on suspicion of violent disorder.
When asked about additional security at the premises, the force said it will not “discuss matters of security”.
However, Foreign Office minister Lord Tariq Ahmad tweeted soon after the attack to say that he was “appalled” and that the British government would always take security at the mission seriously.
"This is a completely unacceptable action against the integrity of the Mission and its staff. The UK government will always take the security of the Indian High Commission seriously,” said Lord Ahmad.
Responding to the incident, London's Mayor Sadiq Khan said he condemned "the violent disorder and vandalism that took place".
"There is no place in our city for this kind of behaviour," he tweeted.
Scotland Yard said it was called to reports of disorder on Sunday afternoon and that a man was arrested as its enquiries continue.
"Windows were broken at the High Commission building,” the Metropolitan Police statement said.
"Officers attended the location. The majority of those present had dispersed prior to the arrival of police. An investigation was launched, and one male was arrested nearby a short time later on suspicion of violent disorder. Enquiries continue,” the statement said.
Diaspora groups also expressed their outrage at the incident, with several gurdwaras among those condemning the violence.
In a joint statement issued from across the UK, British Sikh community leaders said: “Everyone has the right for peaceful protest, but the use of violence or threats against Indian High Commission staff and forcefully trying to remove Tiranga (Tricolour), the national flag of India, is not acceptable and we condemn these actions.
"Such actions cannot achieve anything apart from damaging UK & India ties and our community cohesion.” Jaswinder Kumar, President of the Sri Guru Ravidass Sabha Bedford, and Gurmail Singh, vice-president of the Ramgarhia Sikh Society Bedford were among those to issue similar condemnations.
British Sikh House of Lords peer, Lord Rami Ranger, said the Sikh community is in “shock and disbelief” at how a handful of the misguided bunch can tarnish an illustrious and patriotic community.
“They have also shown total disrespect to Sikh Gurus who paid the supreme sacrifice for their Mother India,” he said.
Sunday's incident came after similar radical actions by Khalistan supporters in Canada and Australia.
On Wednesday, the Honorary Consulate of India in Australia's Brisbane city was forced to close down due to safety concerns after Khalistan supporters organised an unauthorised gathering and blocked the entry of the office.
Several Hindu temples in Melbourne were vandalised by Khalistan supporters in recent months.
India has repeatedly raised the issue with Australian authorities.
Australian Prime Minister Anthony Albanese during his recent India visit assured his Indian counterpart Narendra Modi that Australia won’t tolerate any extreme actions like attacks on religious places.
Canada has also seen a rise in anti-India activities recently by Khalistan supporters who have vandalised some Hindu temples.
Last September, the Ministry of External Affairs issued a statement condemning the rise of hate crimes against Indians and anti-India activities in Canada, expressing their concern with stern language.
Except for the headline, this story has not been edited by The Telegraph Online staff and has been published from a syndicated feed.