US ambassador to the United Nations Susan Rice said the wave of unrest sweeping the Arab world, including the toppling of regimes in Tunisia and Egypt, was a clear signal that societies were ripe for reform.

"What we're seeing across the region is a yearning for change, a hunger for political reform, economic reform, greater representation, and we support that," Rice told NBC's "Meet the Press."

"The message is the same: no violence, respect the universal rights of people to assemble, to protest, to speak, to form political organizations. And get ahead of reform (and) recognize that there needs to be lasting political change."

Critics have slammed Washington for being behind the curve in the Middle East, where deadly unrest is testing the underpinnings of US policy which for decades has sided with rulers who kept a lid on dissent but provided relative geopolitical stability.

Rice insisted that "we don't see a dichotomy or an inconsistency" with pressing for reforms while maintaining allegiances with regimes such as the one in ally Bahrain.

"Throughout the course of this entire administration, we have been saying to our friends and partners in the Arab and Muslim world that there needs to be a process for full reform," she said.

"There are conditions that are unstable. A youth bulge, high unemployment, lack of political openness, and we have pressed publicly and privately for the kind of change that is necessary."

Rice demurred when asked specifically about whether the government in Bahrain, a small but strategic Gulf kingdom that hosts the US Navy's Fifth Fleet, can survive the ongoing protests.

But she made clear that the kingdom must engage the opposition and make substantive changes or risk being swept aside by people power revolts similar to the ones in Tunisia and Egypt.

"We've seen change so rapidly. What we're encouraging governments in the region to do is recognize this is a yearning for change and reform.

"It needs to be respected," she added. "They need to get ahead of it by leading rather than being pushed."

Pressed on the apparent inconsistency of President Barack Obama's administration encouraging President Hosni Mubarak to step down in Egypt while not making the same demand of Bahrain's monarchy, Rice stressed that conditions were different in each country.

"Each of these circumstances will be decided by the people of those countries," she said. "We are not pushing people out or dictating that they stay."