Police scuffled with black-clad anarchists and antiglobalization protesters Monday in the streets of Edinburgh, and 450 demonstrators sat down in the road blocking an entrance to a naval base for nuclear submarines.

The demonstrators at the Clyde Naval Base (search), who protest every year, vowed to shut down the base for Britain's nuclear armed Trident submarine (search) fleet during the G-8 summit meeting. starting Wednesday in Scotland.

"It is vitally important that people make the link between the industrial war machine and the poverty that so many people are suffering from around the world," said protester Jenny Gaiawyn, 26.

As two helicopters circled overhead, helmeted police, including a contingent on horseback, stopped a march by some 300 anarchists and opponents of globalization in the city's financial district, then slowly let them go one by one. Most of the marchers wore black, and some had masks.

There was also a standoff in Edinburgh near the Sir Walter Scott (search) monument where riot police stood three-deep to stop a mix of about 150 clowns, anarchists and local people.

Protesters jumped up and down and blew whistles, stood atop bus shelters and dragged several park benches onto the road. Some directed obscene gestures and shouts at police.

One man stripped off his clothes and walked naked down the street, pursued by reporters.

But there was also a lighter element. Some protesters kissed police riot shields, leaving lipstick marks. A bagpiper wearing a skateboarding helmet provided a musical accompaniment.

Office workers leaned out of windows to watch as one clown waved a carrot at police horse, another tried to tickle their noses with a feather duster.

One protester held up a banner outside Starbucks saying, "abolish capitalism before it kills the planet."

In Gleneagles, where the leaders will meet, mounted police and a mobile surveillance camera unit were seen on the streets. Minor roads were closed, and police roadblocks were set up around the hotel, site of the summit. The hotel was also protected by a 6-foot tall steel mesh fence, a series of watchtowers and a network of surveillance cameras.

About 10,000 officers from all over the country are policing the event.

At Clyde Naval Base, more than 100 police officers were stationed at its entrance and at intervals around its perimeter. They appeared to be adopting a low-key approach aimed at avoiding confrontations with the protesters; no arrests had been reported.

The protesters later broke up into smaller groups and marched around the base's perimeter fence. At several entrance points, groups of between six and 10 sat on the ground and joined hands with plastic piping covering their arms in an often-used tactic that makes it more difficult for police to separate them and remove them from the scene.