Black-clad protesters fought pitched battles with police as the world's most powerful leaders convened on a massively-secured luxury Scottish golf resort to help Africa's poor and curb global warming.

British Prime Minister Tony Blair flew in by helicopter to the French chateau-style Gleneagles complex where he will host the Group of Eight summit, protected by a five-mile (eight-kilometer) no-fly zone, a tethered blimp with infra-red cameras, makeshift look-out posts and 10,000 police.

An hour's drive away in Stirling, activists, some armed with iron bars, smashed cars and hurled bricks through the windows of a Burger King fast-food restaurant. Later, about 200 protesters in hooded tops, scarves obscuring their faces, barricaded roads and hurled missiles at police.

Near the summit site itself in the town of Auchterarder, a rally that

was planned for later in the day was cancelled. Protesters had been planning to mock the G8, dressing up as kilts and wearing masks imitating the leaders of Britain, Canada, France, Germany, Italy, Japan, Russia and the United States.

Blair, who landed in Edinburgh a few hours earlier after a frantic bout of campaigning for London's bid to host the Olympics in 2012, hopes to bridge personal rifts and deep differences to reach a momentous deal to help Africa, perhaps even an agreement to slow global warming.

The three-day gathering, which starts with a dinner hosted by Queen Elizabeth II, is already beset by squabbles over everything from the world climate to the Olympics contest and the quality of British food.

"We set difficult targets and we knew they were difficult targets, but we decided to just go for it and see how far we could get," Blair's

spokesman said Tuesday evening in Singapore, where the Olympic decision will be made.

A commitment by G8 nations to double annual aid to Africa to 50 billion dollars was "close" to being agreed, he said. The major powers have already struck a deal to eliminate 40 billion dollars of debt owed by 18 poor countries, including 14 from Africa, to international institutions.

On climate change, US President George W. Bush appeared determined to give no ground other than conceding that humans do have a role in contributing to a warming of the planet.

"I recognize that the surface of the Earth is warmer and that an increase in greenhouse gasses caused by humans is contributing to the problem," Bush told a press conference in Copenhagen before flying to Scotland.