About 400 protesters, who had been part of a largely peaceful demonstration of some 3,000 people, broke away into a barley field near the fence, an AFP correspondent at the scene said.

Protesters shook at the fence as Group of Eight leaders, including US President George W. Bush, were arriving at the Gleneagles golf resort for a three-day Group of Eight summit.

About 60 to 80 police officers were flown to the site aboard two Chinook helicopters, backed up by other officers who brought in police dogs. The demonstrators were later chased off.

The majority of the 3,000 people on the march stuck to the agreed route through the village of Auchterarder, rallying at a point some 500 meters (546 yards) away from the summit site.

They were blocked by a wire fence and lines of riot police -- some of them on horseback -- guarding the posh Gleneagles resort, the venue of the three-day summit that began Wednesday.

Demonstrators hoisted two large banners, one of them reading "Fight Poverty, Not War, Bring the Troops Home," and shouted "They say drop bombs, we say drop the debt."

Many of the protesters then headed back to the small town of Auchterardar, where they had earlier assembled, accompanied by a bagpiper in full Highland regalia playing "Scotland the Brave."

The trouble at the fence broke out on the return trip.

"The most violent men on earth today are at Gleneagles and they are called the G8," controversial British MP George Galloway told the crowd ahead of the march.

"They won't be wearing hoods or balaclavas but they are responsible for the deaths of millions of people. If the police wanted to do the world a favor they should go into Gleneagles and arrest the lot of them."

Dawn clashes

Police had initially cancelled the demonstration after dawn clashes with protesters -- some armed with iron bars -- in the nearby Scottish town of Stirling but later rescinded the order after reviewing the security situation.

Leaders from Britain, Canada, France, Germany, Italy, Japan, the United States and Russia opened the annual summit with a dinner hosted by Britain's Queen Elizabeth on Wednesday evening.

Starting Thursday they are to debate proposals for increased aid to Africa, debt cancellation and measures to curb global warning.

Activists and non-governmental organizations have faulted the aid proposals as insufficient and maintain that offers of debt cancellation require beneficiary countries to implement trade liberalization and privatization, measures they say increase poverty.