"It is clear that the speech announced the failure of the political programme since Oslo," Taher al-Nunu, a spokesman for the Hamas government said, calling Abbas's address "emotional."

"The speech contained contradictions. He talked about the failure of the peace process and Oslo, and then called for the return to negotiations," Nunu said.

"We repeat that it would be better for Abu Mazen to proclaim the death of the negotiations and of compromise," he added.

Abbas addressed the United Nations General Assembly on Thursday in a speech that pointed a clear finger of blame at Israel for a stalemate in negotiations, and accused the Jewish state of "ethnic cleansing" against the Palestinians.

A year after he called on the United Nations to admit the Palestinians as a full state member, Abbas said he would seek an upgraded status that falls short of full membership through the General Assembly.

Hamas spokesman Sami Abu Zuhri criticised that request saying it was a "unilateral step not agreed upon by the Palestinians."

"There are a lot of questions and observations about the move," he said.

President Barack Obama's administration has offered varied explanations as to who may have been behind the September 11 attack on the American diplomatic mission in Benghazi, drawing criticism from Republican opponents weeks before a US presidential election.

Panetta, repeating Secretary of State Hillary Clinton's comments on Wednesday, said the assault was a "terrorist attack" and also suggested that it took days for the US government to conclude extremists had launched an orchestrated assault.

"As we determined the details of what took place there, and how that attack took place, that it became clear that there were terrorists who had planned that attack, and that's when I came to that conclusion," he said.

"It took a while to really get some of the feedback from what exactly happened at that location."

Some Republican lawmakers have alleged that the Obama administration knew almost immediately afterward that Al-Qaeda was involved in the Benghazi attack, which killed the US ambassador to Libya and three of his staff.

But Panetta said it was too soon to say whether Al-Qaeda or Al-Qaeda-linked groups had a role in the incident.

"As to who was involved, what specific groups were involved, I think the investigation that is ongoing hopefully will determine that," said the former CIA director.

The US military's top officer, General Martin Dempsey, told the same press conference that there had been no warning of a direct threat to the American mission in Benghazi before the attack.

"There was a thread of intelligence reporting that groups in the environment in... eastern Libya were seeking to coalesce, but there wasn't anything specific and certainly not a specific threat to the consulate that I'm aware of," the general said.

The State Department initially maintained the attack arose out of a spontaneous protest against an anti-Islam Internet video made in the United States.