Story highlights People accused of having weapons with a violent intent are among those arrested

Police say they have a plan to deal with street protests

"London is right at the heart of global capitalism," Carnival Against Capitalism group says

The G8 is set to meet next week in Northern Ireland

At least 57 people were arrested in London on Tuesday in connection with plans for anti-capitalist demonstrations before next week's Group of Eight summit, police in Britain said.

Those arrested were accused of possession of weapons with the intent to cause violent disorder, possession of pointed/bladed articles and a variety of public order offenses. Earlier, police in riot gear raided a building in central London.

Britain is hosting the G8 world leaders at a summit next week in Northern Ireland. A "Carnival Against Capitalism" has been planned by demonstrators ahead of the summit.

Demonstrators long have targeted the G8 summit to protest the economic policies of the world's leading industrial powers. The group is made up of Canada, France, Germany, Italy, Japan, Russia, the United Kingdom and the United States.

The Carnival Against Capitalism group said it hasn't negotiated with police and stressed that it won't be controlled. It planned a "mass action" of protests for central London on Tuesday afternoon.

"London is right at the heart of global capitalism," the Carnival group said on its website. "The powerful feel safe in London so long as they go unchallenged."

"Traditionally, carnival is the time where the people take over the streets, the bosses run and hide, and the world gets turned upside down. It is a time to celebrate our resistance and our dreams, to bring music and colour to the streets. And also to show our strength and our anger."

The group said in a statement that the mass actions "will only be as effective as the people participating in them."

"We have not negotiated with the police and we will not be controlled. If we look after each other, stay mobile, don't get caught in kettles and are ready to make quick decisions about what to do next, we can make the most of the day. See you on the streets," the group said.

The London Metropolitan Police says it has "an appropriate police plan in place." There were nearly 1,200 officers on duty as part of Tuesday's policing operation around the G8 summit.