From left, mayors Franklyn Tau of Johannesburg, Won Soon Park of Seoul, Eduardo Paes of Rio de Janeiro, Michael Bloomberg of New York, Babatunde Fashola of Lagos, Gilberto Kassab of Sao Paulo and Eduardo Macri of Buenos Aires at the Rio+C40, a parallel meeting to the Rio+20 on Tuesday. [Photo/Agencies]

The long-awaited draft outcome for the Rio+20 Earth Summit concluded on Tuesday, thanks to compromises made by parties during intense consultations led by Brazil over the past three days.

The outcome text is ready to be submitted for formal adoption by world leaders during the summit beginning on Wednesday.

Chinese Premier Wen Jiabao will join about 130 heads of state, as well as ministers and diplomats from 180 countries and about 50,000 participants, at the summit.

"The draft outcome is not perfect, but acceptable, by taking major concerns of all sides into account," China's assistant Foreign Minister Ma Zhaoxu told reporters on Tuesday.

Generally, the outcome document is "comprehensive, positive and balanced", laying a foundation for international cooperation on sustainable development, Ma said.

The 49-page text reaffirms all the principles of the Rio Declaration on Environment and Development, including "the principle of common but differentiated responsibilities", a major concern of the Group of 77 and China.

The outcome also sets out a process to establish a high-level forum on sustainable development and decisions on establishing sustainable development goals to be adopted by all countries.

"China is here for the promotion of sustainable development. That's our goal," Ma said.

The Chinese delegation has played an "active and constructive" role during the entire process of the negotiations and made a great contribution to an early consensus, while safeguarding the overall interests of China and other developing countries, he said.

Ma called on all parties to continue working closely to achieve a "comprehensive, active and pragmatic" outcome from the summit, to convey a clear and strong signal to the world about promoting sustainable development.

He also thanked host country Brazil's efforts during the informal consultations.

Delegates showed "extremely constructive spirit and flexibility over the past two and a half days", said Brazil's Foreign Minister Antonio Patriota.

"We have reached the best possible balance at this point …We consider that the spirit of Rio has been kept alive after 20 years," he said.

The outcome does not include all "high-flying expectations", but compromises were found in a difficult international environment, as economic crisis and recession have affected many countries, German Environment Minister Peter Altmaier told China Daily.

"There are so many conflicting interests in the debate. The Brazilian presidency last night wanted to conclude the negotiations … We have been quite successful of doing this, but as we all know, that's a compromise for all relevant parties," he said.

Observers said expectations of the summit have been lowered due to the worsening global financial crisis, and developed countries are reluctant to offer more.

French President Francois Hollande will attend the summit, but US President Barack Obama, UK Prime Minister David Cameron and German Chancellor Angela Merkel will be absent.