“Our current best assessment, based on the information we have at present, is that, in fact, what this began as, it was spontaneous – not a pre-meditated – response to what had transpired in Cairo,” she said on ABC News’ “This Week.” “We believe . . . that a small number of people came to the . . . consulate . . . to replicate the sort of challenge that was posed in Cairo. And then as that unfolded, it seems to have been hijacked, let us say, by some individual clusters of extremists who came with heavier weapons.”

A senior intelligence official who asked not to be further identified because he was not authorized to speak publicly on the subject offered a similar assessment. “Simply put, while everything is still under investigation, the available information suggests the protests in Cairo inspired what the attackers decided to do later that night in Benghazi,” the official said. “Right now, this points to a plan that was hatched opportunistically that day. Of course, if credible new information suggests otherwise, the investigation will pursue those leads.”

In contrast, Magarief, the Libyan official, told CBS News’ “Face the Nation” that the attack was “planned by foreigners, by people who entered the country a few months ago, and they were planning this criminal act since their arrival.”

The foreigners included people from Algeria and Mali, the North African country whose northern half has been overrun by Islamic militants linked to al Qaida and whose arms are thought to have come from looted Gadhafi storehouses.

In a related development, Wanif al Sharif, the deputy interior minister who was in charge of eastern Libya and headed the investigation, was fired, according to the Libya Herald, because of the attack. Sharif was the only Libyan official to publicly say that there had been a protest before the attack. He didn’t respond to calls Monday seeking comment.

Even before the assault, many Libyans had complained about deteriorating security in Benghazi, where the uprising against Gadhafi first erupted. Scores of rogue militias have been drafted by the government to provide security in the absence of a regular force, and the role of extremists, including members of Ansar al Shariah, has been controversial.

The city is divided block by block among the groups, which have kept the weapons they procured during the uprising. Many of the militias occupy bases lined with tanks and machine-gun mounted trucks and are led by self-styled colonels.

Every time there was a bombing or other attack, Sharif blamed remnants of Gadhafi’s regime, despite evidence that groups empowered by the state were behind the violence, said Michel Cousins, the editor of the Libya Herald. The attack on the compound was the last straw for Libya’s first elected government, he said.

Magarief has been a critic of the Interior Ministry before, blaming it last month for involvement in the destruction of mosques and shrines associated with the moderate Sufi strain of Islam. Interior Minister Fawzi Abdel Al handed in his resignation after Magarief’s criticism, but he rescinded it two days later, saying the threat from Islamist militants was too great for him to step down.

Nancy A. Youssef contributed reporting from Cairo.