The Obama administration said Sunday that it is "gravely concerned" about reports of the deadly suppression of democracy demonstrations in Libya.

A statement was issued by the State Department soon after U.N. Ambassador Susan Rice did not directly answer a question on Sunday morning's "Meet the Press" about whether dictator Moammar Gadhafi is killing protesters.

"The United States is gravely concerned with disturbing reports and images coming out of Libya," State Department spokesman P.J. Crowley said in a statement. "We are working to ascertain the facts, but we have received multiple credible reports that hundreds of people have been killed and injured in several days of unrest — and the full extent of the death toll is unknown due to the lack of access of international media and human-rights organizations."

The death toll Sunday was estimated at more than 200 in six days of protests, with reports of unarmed Libyans being shot mostly in the head, neck and chest. The Guardian reported some opposition sources putting the number as high as 500 dead.

"We have raised to a number of Libyan officials, including Libyan Foreign Minister Musa Kusa, our strong objections to the use of lethal force against peaceful demonstrators," Crowley said. "We reiterated to Libyan officials the importance of universal rights, including freedom of speech and peaceful assembly. Libyan officials have stated their commitment to protecting and safeguarding the right of peaceful protest.

"We call upon the Libyan government to uphold that commitment, and hold accountable any security officer who does not act in accordance with that commitment," he added.

Reports that have emerged from Libya include government snipers taking out protesters or firing assault weapons at them.