PM Narendra Modi was greeted by demonstration both against and in his support in UK.London:  Demonstrations against Prime Minister Narendra Modi's visit to the UK took a violent turn and an Indian flag was torn down from one of the official flagpoles set up for the 53-nation Commonwealth Heads of Government Meeting on Wednesday.

PM Modi, who is in the UK for bilateral talks and the Commonwealth meet, was greeted by protesters as he met his British counterpart Theresa May.A senior journalist from an Indian news channel covering the protests was caught in the violent scrum sparked by aggressive pro-Khalistani protesters and Scotland Yard officers on duty had to step in to the rescue."We have expressed our concerns with the British authorities and they have apologised for the incident.

We have been warning against some of these elements out to make trouble and they have assured us of action.

The Indian flag has now been replaced," a senior Indian official associated with the PM's visit told news agency PTI.The pro-Khalistani demonstrators from Sikh Federation UK and demonstrators from the so-called "Minorities Against Modi" group, led by Pakistani-origin peer Lord Ahmed, were among nearly 500 protesters who descended upon London's Parliament Square.

These included groups led by some Kashmiri separatist groups and at one point, some of them had surrounded the Mahatma Gandhi statue at the square with their banners and flags. An Indian flag was taken down by protesters in Parliament Square in London.Officials involved with the prime ministerial visit to the UK had said that protests and demonstrations are "part and parcel of any democratic society" as long as they remain peaceful.

There are now concerns that some of the more aggressive elements hijacked the tone of the protests.Earlier on Wednesday, flash mob of sari-clad women with dhols set the tone for the pro-PM Modi crowds opposite 10 Downing Street as he arrived for his breakfast meeting with British Prime Minister Theresa May.

They were joined by the Friends of India Society International (FISI) group, which spearheaded a crowd of Indian diaspora from across the UK waving banners such as Chak De India and Jai Hind outside Downing Street and nearby Parliament Square."We want to welcome the Indian PM to the UK and show him the diaspora support he enjoys," said one of the members of the gathering.On the other side, the anti-Modi protesters from Caste Watch UK and South Asia Solidarity group waved banners against the Prime Minister."Hindu nationalism must be curtailed to avert India sliding towards wholesale dictatorship threatening democratic fabric, rule of law and the unity of India," a Caste Watch UK spokesperson said.They were joined by other protesters carrying images the 8-year-old rape victim from Kathua in Jammu and Kashmir, and Gauri Lankesh, the Indian journalist who was shot at her doorstep last year.The group also included representatives of several Indian women's groups in the UK, wearing white as part of their silent protest."I am Hindustan, I am ashamed," read their placards alongside banners such as 'Beti Bachao' and 'Politics minus rape'.