WASHINGTON – Top US intelligence officials faced tough questions from lawmakers Wednesday over Egypt's Muslim Brotherhood, acknowledging the spy agencies lack certainty on the opposition group's views.

The intelligence chiefs struggled to answer questions about the agenda of the Islamist movement, amid accusations the spy services were caught off-guard by the unrest in Cairo that forced Egypt's strongman Hosni Mubarak to step down last week.

National Intelligence Director James Clapper told senators at a hearing that the group did not speak with one voice and that he was unsure about the Muslim Brotherhood's stance on Iran, the Egypt-Israel peace treaty and weapons smuggling into Gaza.

"It's hard to at this point to point to a specific agenda of the Muslim Brotherhood as a group," he said.

A dissatisfied Dianne Feinstein, chair of the intelligence committee, said the spy agencies needed to do better at understanding a group that could shape events in Egypt's political vacuum.

"From an intelligence perspective, it is critical that we know what is that position (of the Muslim Brotherhood) and what is apt to happen. Egypt is the key country in the Middle East. And I worry about that," she said.

Clapper said the intelligence agencies would bolster their efforts.

"This is obviously something we're going to watch. We're going to have to step up our observation," he said.

US intelligence agencies enjoyed close ties over three decades with the Mubarak regime, which devoted huge efforts to tracking and suppressing the Muslim Brotherhood.

Some critics say the CIA developed a blind spot in its reliance on Arab regimes to counter Islamist militants, failing to closely track opposition movements and social unrest in the Middle East.

American spies cultivated relations with their Egyptian counterparts but often at the expense of understanding "the world of the protesters," columnist David Ignatius wrote in The Washington Post last week.

Feinstein slammed the intelligence agencies for their work on the Mideast turmoil, saying the services seemed to miss the importance of social media and that the US military's Central Command had produced more useful reports.

Clapper reinforced doubts about the intelligence agencies last week when he described the Muslim Brotherhood as "largely secular." But at Wednesday's hearing, he admitted he made a mistake.

"The Muslim Brotherhood is obviously not secular. What I had hoped to convey, and would like to clearly state here, is that the Muslim Brotherhood in Egypt tries to work through a political system that has been largely secular in its orientation," he said.

Clapper, a veteran of the intelligence world, said the Islamist group had diverse "factions" with "a conservative wing whose interpretation of Islam runs counter to broad electoral participation, and a younger, more liberal wing who are more inclined to work through a secular, political process."

CIA Director Leon Panetta told senators the Muslim Brotherhood was not "monolithic" but that the intelligence services were closely following the organization, which he said included "extremist elements."

The future role of the Muslim Brotherhood is the subject of heated discussion in Washington, with some lawmakers warning the group harbors hardline goals.

Citing the unrest in Egypt and Tunisia, Panetta has announced a 35-member task force that is supposed to improve the CIA's intelligence gathering on trends that can fuel political upheaval.

The task force will focus on tracking popular sentiment, opposition groups and the role of the Internet.