Palestinians are pushing for full representation as a state at the UN Rio+20 summit on sustainable development, but the issue will have to be decided by world leaders, according to officials.

"We expect full-status participation because we already have it in UNESCO and we have ties with Brazil (the host country which recognizes the Palestinian state) and with more than 130 countries," Palestinian ambassador Ibrahim Alzeben told AFP.

The issue is generating disagreement among UN delegations. The Palestinian Liberation Organization has observer status at the United Nations and the Palestinians are pushing for full membership in the world body.

"There are discussions" on the issue and "no clarity" on how the Palestinians should be represented, said Nikhil Seth, head of Sustainable Development at the UN.

The official pointed to two resolutions applied by the UN for its meetings, one by the UN General Assembly which convened Rio+20 and grants the Palestinians observer status and another used in the past that allows the participation of observers as states in some occasions.

The final decision will be made at a procedural session when the official Rio+20 summit opens on Wednesday, Pragati Pascale, a UN spokeswoman for the conference, said.

The Palestinians have been members of UNESCO since October, a decision that was opposed by the United States and Israel. "We are still hoping that the world will recognize our right," said Alzeben, who announced that the Palestinian delegation will be led by foreign minister Riyad al-Malki.

The Rio+20 conference, which comes 20 years after the First Earth Summit here and runs through June 22, aims to reach common ground on sustainable development that would reconcile economic growth with poverty eradication and environmental protection.