Talks on a new global charter to protect the environment and eradicate poverty were heading into overtime Friday as officials admitted they faced a battle to seal a deal ahead of a UN summit.

The cornerstone document of the June 20-22 Rio+20 summit aims at setting a path for nurturing the planet's natural bounty and promoting green growth.

But after five months of wrangling, talks on a draft entered their final scheduled day on Friday with agreement on only 28 percent of the 81-page text, officials said.

Responsibility for steering the haggle was expected to be handed on Saturday to Brazil, the conference host, said Nikhil Seth of the UN's Division for Sustainable Development.

"It's everyone's hope that by (June) 19 at the latest, everything will be wrapped up," he said.

"There is a sense of optimism, but in every room there is a sense also that the enemy now is time."

Brazilian delegation chief Luiz Alberto Figueiredo, confirming the target date, said "we have no intention to hand undecided issues to heads of state."

Ahead of next week's UN summit, hundreds of corporate leaders launched a four-day forum here Friday to discuss how the private sector could help advance sustainable development goals.

In opening remarks, Georg Kell, executive director of the UN Global Compact, underscored the key role of "innovation and collaboration" in the process.

The Global Compact, a UN initiative to encourage businesses worldwide to adopt sustainable and socially responsible policies, has 7,000 corporate participants in 135 countries.

Forum organizers said private-public partnerships and more than 100 corporate commitments would be announced and recommendations would be submitted to Rio+20 summit leaders next week.

The Conference on Sustainable Development is the 20-year followup to the Earth Summit, when UN members made historic agreements to combat climate change, wildlife loss and desertification.

An expected turnout of 116 heads of state or government will cap a week-long gathering of as many as 50,000 activists, business executives and policymakers.

Progress on the so-called outcome document has been mired by discord, often pitching developing economies against rich ones.

"There are lively discussions still going on," the US special envoy for climate change, Todd Stern, said in a conference call with journalists. "There's still a lot to be wrestled with."

Problems include a set of sustainable development goals to succeed the UN's Millennium Development Goals, due to expire in 2015, to encourage the green economy and mustering funds to promote sustainable development. Poorer countries are calling for $30 billion a year.

But another area of friction is over how or whether to reaffirm the "Rio Principles" set down in the 1992 summit, which say countries have "common but differentiated responsibilities."

The phrase is designed to ensure that poor countries do not have to shoulder the same burden as rich countries in fixing Earth's environmental problems.

But Stern was scathing, saying the phrase belonged to an era when China and other countries that today are emerging giant economies were far poorer and less able to contribute.

The summit is taking place against a backdrop of ever-worsening news on the environment, while financial crises in rich economies have slashed the political will for concessions.

A colorful counter-conference got under away at a Rio park, with the dramatic appearance of 82-year-old Amazonian chief Raoni, stomping and brandishing a club.

The "People's Summit" will feature several different demonstrations, including a main march expected to draw 50,000 people on June 20, when the official Rio+20 gets underway.

Civil society kicks off colorful Rio+20 counter-summit
Rio De Janeiro (AFP) June 15, 2012 - Indigenous and religious groups kicked off a colorful summit Friday as a counterpoint to the Rio+20 conference on sustainable development, calling on nations to do more to protect the planet.

The so-called "People's Summit" got under way at Flamengo park, with the dramatic appearance of 82-year-old Amazonian chief Raoni, stomping and brandishing a club.

"I am still alive to fight against what the white man is doing to us and nature," howled the respected chief of the Kayapo tribe to a crowd of hundreds of people representing various religious and indigenous groups.

Raoni earned worldwide fame in the 1980s for teaming up with British rock star Sting for his defense of the rights of indigenous peoples.

"Our planet is under threat. The number one enemy of mankind is our current lifestyle," said Professor H.M. Desarda of Hyderabad University in India. "Earth has enough for everyone. Need but not greed."

"We are concerned about the future of the environment. We want to know what governments plan to do with the peoples who have always protected the forest," said Irineu Baniwa, an indigenous Brazilian who came from Sao Gabriel da Cachoeira in the northwestern state of Amazonas bordering Venezuela.

"We want economic alternatives for the products of our lands," he added, slamming developed countries for polluting the planet.

Marcelo Rey said he came to Rio to publicize his Afro-Brazilian Candomble religion, which he said "best preserves nature".

"I came here to try to learn about ways of combating climate change. We need to work outside the system and we have a lot to learn from native Indians," said 23-year-old Erynne Gilpin, an indigenous Canadian activist and student from London, Ontario.

Some 400 representatives of 20 Brazilian indigenous groups including the Guaranis, Tikunas, Tukanos, Gavioes, Kaiapos, Xavantes and Bororos are taking part along with 1,200 natives from Canada, the United States, Colombia and Nicaragua.

Organizers say they expect 15,000 people daily at the gathering, an initiative of 200 ecological groups and social movements from around the world opposing what they view as capitalist attempts to hijack the "green economy" concept.

The concept, meant to reconcile economic growth with poverty eradication and environmental protection, will be hotly debated by 116 world leaders at the official Rio+20 summit on June 20-22.

The UN-sponsored event marks the 20th anniversary of the Earth Summit -- a landmark gathering that opened the debate on the future of the planet and its resources.

Over the next few days, the "People's Summit" will feature several different demonstrations, including a main march expected to draw 50,000 people on June 20, when the official Rio+20 meeting gets under way.

A women's rally is scheduled for Monday along with a rally to protest a new forestry code in Brazil that would ease restrictions on forest protection and which environmentalists sees as a threat to the Amazon rainforest.