Repeatedly interrupted by jeers and protests, Secretary of State Colin Powell defended the United States' environmental record and its efforts to help the poor in the developing world Wednesday, the closing day of the World Summit.

"The U.S. is taking action to meet environmental challenges, including global climate change," Powell told delegates at the summit.

The United States has been criticized for President Bush's decision last year to reject the Kyoto Protocol, which many countries view as crucial for reversing a global warming trend blamed for cataclysmic storms, floods and droughts.

The United States has said it was taking many other actions to fight global warming, but the international agreement's strictures were inappropriate and too costly for the U.S. economy.

Washington also had been hammered for resisting binding targets to increase the use of renewable energy sources, and for Bush's decision not to attend the summit.

As Powell spoke, delegates from non-governmental groups in the audience repeatedly interrupted him, shouting "Shame on Bush." Two people held up a banner reading, "Betrayed by governments." At least two people were removed by security.

Powell looked annoyed, answering back "I have now heard you," at one point, then soldiering ahead with his speech.

South African Foreign Minister Nkosazana Dlamini-Zuma, who was chairing the session, yelled at the hecklers to stop and called the outbursts "totally unacceptable."

The boos and jeers began when Powell criticized the government of Zimbabwe for exacerbating the food crisis in that country and pushing "millions of people to the brink of starvation."

He also criticized Zambia, which is also facing a hunger crisis, for rejecting genetically engineered corn that Americans eat every day.

However, much of his speech focused on outlining America's commitment to the developing world and the environment.

"The American soul has always harbored deep desires to help people build better lives for themselves and their children," he said.

"We have reaffirmed the principle that sound economic management, investment in people and responsible stewardship of our environment are crucial for development."

Before his speech, Powell met with U.N. Secretary-General Kofi Annan.

The 10-day summit ending Wednesday was envisaged as an unprecedented global gathering to refocus the world's attention on the plight of the poor and the destruction of the environment.

However, many activists lashed out at the agreements reached here and staged a symbolic walkout Wednesday morning.

While there were a few marginal achievements -- mainly in the protection of fisheries and plans to bring sanitation to the poor -- much of the summit was a desperate fight to stop governments from weakening already existing agreements, activists said.

"We're running on a treadmill. We are running just as fast as we can to prevent ourselves from moving backward," said Andrew Deutz, an official with the World Conservation Union. "It's a missed opportunity."

Late Monday, negotiators resolved the main sticking points in a 70-odd page plan to turn commitments made at the 1992 Earth Summit in Rio de Janeiro into reality. Most of the items were geared to helping the world's poorest people without polluting.

After losing its push for targets on the use of wind and solar energy, the European Union said it would form a coalition of "like-minded countries and regions" willing to commit to strict timetables for increasing renewable energy.

Many developing countries had sided with the United States and Japan against including the targets in the summit's plan, arguing they were a rich country's luxury.

The text agreed to late Tuesday includes a commitment to "urgently" increase the use of renewable energy sources, but says cleaner use of fossil fuels is also acceptable, diplomats said.

British Environment Minister Margaret Beckett called the plan "a generous and serious and substantial outcome."

But Sen. Bob Brown from Australia's Greens party lambasted the energy compromise.

"The wealthy nations have their heads in the sand," he said. "The world's being let down. The interests of the next generation have been appallingly disenfranchised."

Dropped language linking women's health care with human rights became a sticking point in 11th hour deliberations, but was restored before the plan was officially adopted by the summit's main committee of ministers.

India's foreign minister, Yashwant Sinha, said his country was happy with agreements aimed at poverty eradication, but the main success here was the gathering itself, bringing together tens of thousands of business leaders, civic groups and government officials to discuss issues too often overlooked.

"In terms of the richness of participation, this conference has been outstanding," he said. "It has not been the usual government representatives talking to each other."