US Secretary of State Hillary Clinton last night flew to Geneva for talks with European foreign ministers and diplomats from the Middle East and Africa in an attempt to further coordinate the international response to the crisis in Libya.
he UN Security Council on Saturday unanimously imposed what Washington claimed were "biting sanctions" including travel bans and asset freezes on Col Gaddafi and his family.
The resolution adopted by the 15-nation council also called for the immediate referral of the crackdown to the International Criminal Court in The Hague for investigation and possible prosecution.
Washington is also considering including a "no-fly" zone to try to stop Gaddafi's suppression of anti-government protests.
Yesterday both Mrs Clinton and President Barack Obama toughened their rhetoric, saying Gaddafi must depart now.
In London, Foreign Secretary William Hague, who will also attend the Geneva talks, said the international community was not prepared to negotiate. He said: "Clearly we're not going to get into a negotiation with Colonel Gaddafi... he must go."
He added: "Throughout these crises in Egypt and Tunisia we've been careful to say it's the people of these countries who must own the solution. But the people of Libya have risen up against Colonel Gaddafi."
He also added: "Last night, I signed a directive revoking his diplomatic immunity in the United Kingdom but also the diplomatic immunity of his son, his family, his household. So it's very clear where we stand on his status."
US officials said Mrs Clinton's trip is aimed at coordinating the international response, insisting that the world "speak with one voice" on stemming the violence and bringing Col Gaddafi to justice.
The Obama administration had been criticised by human rights groups for moving too slowly on Libya. But White House officials said fears for the safety of Americans in the country had tempered Washington's response to the turmoil.
In a statement on Saturday, Mrs Clinton said the US was working to mobilise a strong and unified response from the international community, and echoed Mr Obama's demand for Col Gaddafi to step down.
"We are also working with partners to determine how to provide humanitarian assistance to those in need," she said.