Demonstrator in central London appeared to try to throw himself from a rooftop
A man has apparently tried to throw himself off the roof of a building during anti-G8 protests before being pinned down by police officers.Sky News' Jason Farrell said the protester appeared on the roof of a central London building, shouting at officers who were wearing climbing equipment.
He then ran towards the edge before he was pulled back and wrestled to the ground by police. He has been taken to hospital.
Around 100 police officers were in Soho where protesters with banners were believed to be occupying the former police station in Beak Street.
Police are thought to have entered the building with a search warrant after receiving intelligence that people there were in "possession of weapons and were intent on causing criminal damage and engaging in violent disorders".
More than six people have been arrested so far over the protests for alleged offences including possession of articles with intent to commit criminal damage, assault on police, criminal damage, possession of an offensive weapon and failing to remove a face covering.
A small number of rallies were held in Oxford Street, Regent Street and Piccadilly Circus during the "Carnival Against Capitalism" before the two-day summit, hosted by Britain, in Northern Ireland next week.
Some of the world's biggest hedge funds, private equity firms and banks have warned their staff to take precautions in the event of disruption after similar protests in recent years led to violent clashes with police, vandalism and buildings being temporarily occupied.
Westminster City Council cabinet member for city management Ed Argar said: "Our warden teams will be working with police to manage the streets and we also have clean-up crews on standby.
"Everyone respects the right to legitimate protest and I hope this will be a day without incident.
"However, business people, shop staff and visitors have the right to go about the West End without intimidation or interference and we will do our best to ensure the centre of London runs smoothly."
There were reports on Twitter of a strong police presence in the Oxford Circus and Regent Street area of central London and Golden Square, close to Beak Street.
Designer Jamie Rees, tweeting under @jamie--rees, reported: "Locked into work. Literally. G8 protestors outside targeting Golden Square."
Another Ed McClaran, @edmcclaran, tweeted: "Big G8 protest outside our offices today. People chaining themselves to railings. Why they are in the West End and not the City, I don't know."
Police protection of landmark sites across Belfast has been tightened in advance of the conference next week.
The leaders of the world's eight wealthiest countries, including Russian President Vladimir Putin and German Chancellor Angela Merkel, are due to meet at the luxury Lough Erne resort in Co Fermanagh.