LONDON - Defence Secretary Leon Panetta said the U.S. is working with the British and Algerian governments to assess what is happening on the ground at a natural gas complex in the Sahara where Islamic militants are holding hostages from at least 10 countries.

The fate of many of the captives remained uncertain.

Speaking Friday at Kings College in London, Panetta said the U.S. is "working around the clock to ensure the safe return of our citizens."

Panetta said the terrorists should be on notice they will find no sanctuary in Algeria or North Africa and said anyone who looks to attack the U.S. will have "no place to hide."

Panetta met later Friday with British Prime Minister David Cameron. Discussion of Islamic militant operations in Mali and Algeria dominated the unscheduled meeting, senior U.S. defence officials said, though the two also discussed budget issues, Syria, Iran and how they can work with other countries to address counter-terrorism.

Senior U.S. defence officials said the two talked in-depth about Algeria, exchanging views and comparing notes about the situation unfolding there.

In Washington, the White House said President Barack Obama was being briefed Friday by his national security team. His top aides were in touch with Algerian officials as well as BP's security office in London. BP jointly operates the natural gas plant.

Administration officials, seeking to explain the lack of information from the U.S., said the situation on the ground was fluid, and officials did not want to put the hostages at further risk by providing real-time updates.

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