JOHANNESBURG, South Africa -- Thousands of peaceful demonstrators, disillusioned by squabbling and compromise, marched to the World Summit on Saturday, demanding immediate action to save the planet and its poor.

Inside the summit building, negotiators slogged through a sixth day in an elusive hunt for language to protect the environment and get clean water, sanitation and health care to more than a billion people who live without them.

"We must liberate the poor of the world from poverty," South African President Thabo Mbeki demanded at one pre-march rally, calling for an end to the "global apartheid" that divides the rich and poor.

"It is easy for all of us to agree on nice words," he said. "Now has come the time for action."

But nice words don't come easily. For nearly a week, negotiators have toiled, harangued and cajoled over just a few phrases in the 70-odd page summit action plan.

"The clock is ticking and there is still a lot to sort out," Lucian Hudson, the spokesman for the British delegation, said Saturday.

More than 20 world leaders, including Zimbabwe's Robert Mugabe, arrived in South Africa on Saturday and the number was expected to reach 109 before the summit ends Wednesday with a final plan of action.

Negotiators worked long hours Friday and Saturday but remained at odds over the language on energy, biodiversity, sanitation, climate change and reducing poverty.

John Ashe, chairman of the group working on the text on finance, said Saturday evening he believed issues involving export subsidies and how to define globalization were almost resolved.

However, delegates from Europe and Asia said they doubted an accord could be reached on several remaining issues, especially deadlines for compliance.

Adding to the sense of frustration is the choice of the site itself. South Africa is the most developed country on the least developed continent. Johannesburg itself is a study in contrasts: a city of gold and a beacon of conspicuous consumption nestled among the sprawl of teeming and squalid townships.

From their shacks, the poor here can see the benefits of a better life. Their growing impatience reflects the discord of the poor elsewhere over the weary wait for clean water, sanitation, electricity, better housing, health care and education for their children.

"What is this summit doing for us? It is providing for the rich, not the poor," said one demonstrator, Mathius Ledwaba.

Many countries, both rich and poor, have resisted the summit's goals. For example, the European Union has shown reluctance to discuss eliminating agricultural subsidies while developing countries have sided with the Bush administration against demands for renewable energy.

But the protesters' lament is often repeated by activists and delegates from poorer nations who blame the slow progress on the United States with its wealth and disproportionate consumption of the Earth's bounty.

Many in Saturday's two demonstrations chanted anti-American slogans and carried banners that portrayed President Bush as a "toxic Texan."

The U.S. delegation counters that Americans have taken the lead on commitment and action, announcing programs and partnerships worth billions of dollars.

"In my opinion, it represents the largest package of world assistance in history," said Assistant Secretary of State John Turner.

Turner's message failed to reach many of the more than 5,000 demonstrators who marched for hours to the summit in the lavish suburb of Sandton from Alexandra, an overcrowded township of tin shacks and open sewers.

South African security forces, determined to avoid repeats of violent anti-globalization protests earlier in Seattle and Genoa, Italy, reinforced an already tight security cordon around the conference grounds.

Police with riot helmets and shields stood shoulder-to-shoulder near the conference hall. They brought in armored vehicles, water cannons and strung coils of barbed wire at key points within the steel-and-concrete perimeter fence.

Demonstrators were noisy, but not combative.