Palestinian National Authority President Mahmoud Abbas complained that U.S. President Barack Obama "is doing nothing for the peace process" in the Middle East so far.

"For now he is doing nothing, but he has invited us to revive the peace process. I hope that in the future he can play a more important role," Abbas said in an interview published Tuesday by the Argentine daily Clarin.

Instead, Abbas again called upon Brazilian President Luiz Inacio Lula da Silva to take a more active role as mediator in the Middle East.

"He can do it, because he has good relations with the two parties in the conflict and I think he can help," said Abbas, who has visited with Lula in recent days, along with separate visits from President Shimon Peres and Iranian President Mahmoud Ahmadinejad.

Abbas expressed the hope that "the United States [will] put pressure on the Israelis to abide by international law, so that the roadmap can be implemented."

Abbas, who was in Argentina Tuesday, said he was pleased with the results of his ongoing South American tour, which initially took him to Brazil and was also to include a stay in Chile.

"President Lula can now take on a mediating role because he has ties of trust with the two parties in the conflict. Besides, he also has a good relationship with the U.S. government. Brazil can play that role," Abbas stressed.

He anticipated, however, that the Palestinians will not make any more concessions than they have already made.

"We accepted to have only 22 per cent of Palestine, and that is the biggest concession. And we also accepted that Israel had 78 per cent. So, what kind of concessions are they expecting from us?" he said.

"Now we are ready to announce our independence if the Israelis will allow us to," he said.

Abbas said, however, that independence would not be declared unilaterally.

"[The Israelis] are trying to say that we the Palestinians are seeking a unilateral decision. We are not seeking a unilateral decision," he said.