Protests have been held in Scotland's capital, sparking scuffles between riot police and demonstrators two days before leaders of the world's richest nations hold a summit nearby.
Several people were detained in Edinburgh, and at least two police officers were injured in clashes, while several people fainted in the crush.
The demonstrations began peacefully as protesters, banging drums and shaking bells, marched and danced into waiting police containment cordons in Edinburgh's financial centre.
The demonstrations were part of an array of protests that began on Saturday with a 200,000-strong march through the city calling for an end to poverty in the developing world, especially Africa.
Leaders of the Group of Eight industrialised nations meet amid tight security from Wednesday to Friday at the nearby Gleneagles Hotel, tasked with tackling African poverty and devising a strategy against global warming.
On Monday, black-clad and masked members of the Black Bloc, an anarchist group based in Germany and Scandinavia that has been prominent in protests at past G8 summits, mingled with other demonstrators dressed as fairies and clowns.
Trouble began when about 30 members of the Black Bloc, among about 200 protesters trapped between lines of police, pushed and scuffled with police officers.
Among the activists were people wearing military fatigues, many with painted faces and red noses, who described themselves as the "clandestine insurgent clown rebel army".
About 10,000 officers from across the country are policing the event.
Mindful of the violence that erupted at previous G8 summits in Genoa, Italy, in 2001 and Evian, France, in 2003, Scottish police have been taking no chances.
At the Clyde Naval Base in western central Scotland, about 450 demonstrators blocked the road, vowing to shut down the Trident submarine base for the day.
The Trident protesters, who stage the event every year, enjoyed increased news coverage this year because of the big media presence in Scotland for the G8.
PHOTO CAPTION
A protester faces police officers as he participates in a peaceful rally in Edinburgh. (AFP)