|Obama said the US will not stand idly by in the face of actions that undermine global peace [AFP]
The US president has told Libyan leader Muammar Gaddafi that terms laid out in the UN Security Council resolution seeking to impose a no-fly zone over his country are not negotiable.
In a televised statement from Washington on Friday, Barack Obama said Gaddafi had the "choice" to declare a ceasefire or face "consequences".
"Let me be clear: These terms [in the resolution] are not negotiable," said Obama.
"These terms are not subject to negotiation. If Gaddafi does not comply with the resolution, the international community will impose consequences. The resolution will be enforced through military action."
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Obama said the US was prepared to act as part of the international coalition, adding that US leadership was "essential in shaping the conditions for the international community to act together".
"The US, the United Kingdom, France and Arab states agree that a ceasefire must be implemented immediately," Obama said.
"That means all attacks against civilians must stop and Gaddafi must stop his troops from advancing on Benghazi; pull them from Ajdabiya, Misurata and Az Zawiyah and establish water and electricity supplies to all areas. Humanitarian assistance must be allowed to reach all people of Libya."
Obama's comments came hours after Moussa Koussa, Libya's foreign minister, announced a ceasefire on state television, although witnesses in Misurata speaking to Al Jazeera said fighting continued just after the announcement.
The Security Council adopted Resolution 1973 on Thursday, authorising a no-fly zone and allowing countries like France and the UK to use planes over Libya's air space in a bid to protect civilians from air power.
'Gaddafi lost legitimacy'
Obama said Libyans were demanding their universal rights and a government that is accountable to them and responsive to their aspirations but they were met with an iron fist.
"Muammar Gaddafi clearly lost the confidence of his own people and the legitimacy to lead," Obama said, adding that the US will not stand idly by in the face of actions that undermine global peace and security.
Earlier, David Cameron, Britain's prime minister, reacted to the ceasefire announcement, saying Gaddafi would be judged by "his actions not his words".
"What is absolutely clear is the UN Security Council resolution said he must stop what he is doing - brutalising his people," Cameron told the BBC.
"If not, all necessary measures can follow to make him stop. That's what we agreed last night; that's what we are preparing for and we'll judge him by what he does."
Cameron said before the BBC interview that Britain was about to start sending fighter jets and surveillance aircraft to military bases in the Mediterranean in preparation for a no-fly zone.
Speaking to parliament, he said Tornado and Typhoon jets would be deployed imminently along with surveillance and re-fuelling planes.
"Preparations to deploy these aircraft have already started and in the coming hours they will move to airbases from where they can start to take the necessary action," he said.
Hillary Clinton, the US secretary of state, echoed Cameron's views and said the "final result" of the UN's resolution on Libya must be Gaddafi's departure.
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"Colonel Gaddafi's refusal to hear the repeated calls up until now to halt violence against his own people has left us with no other choice but to pursue this course of action," Clinton said.
"While this resolution is an important step, it is only that - an important step. We and our partners will continue to explore the most effective measures to end this crisis."
Clinton will be travelling to Paris on Saturday for a "meeting with US allies and partners about the enforcement of the resolution," Obama said.
Jose Luis Rodriguez Zapatero, the Spanish prime minister, also warned that the international community "will not be fooled" by Gaddafi's government and will verify compliance with the UN resolution.
Gaddafi's forces have retaken key cities that pro-democracy fighters had captured and and are heading towards Benghazi in the east, the stronghold of the opposition where protests began over a month ago.
Source: Al Jazeera and agencies