US Secretary of State Hillary Clinton met a Libyan opposition leader in London on Tuesday while Washington prepared to send an envoy soon to the rebel stronghold of Benghazi, officials said.
Her talks on the sidelines of an international conference on Libya marked an increase in US contact with the Transitional National Council (TNC), from whom US officials say they are trying to obtain a "clearer picture."
However, the United States has stopped short of officially recognizing the body, which it hopes will further the aims of a future democratic Libya.
It was Clinton's second meeting with Mahmud Jibril, who handles foreign affairs for the TNC, following a first on 15 March in Paris where she was attending a Group of Eight meeting.
Clinton was to seek Jibril's impression of the situation in Libya where rebels are beating back Muammar Gaddafi's forces amid allied military intervention.
Since she last met Jibril, the TNC has "put out a series of what we view to be constructive public statements about their vision of a future for Libya," a senior US administration official told reporters on condition of anonymity.
In a statement Tuesday, the rebel body said it recognised there was "no alternative to building a free and democratic society and ensuring the supremacy of international humanitarian law and human rights declarations."
Gene Cretz, who was US ambassador in Tripoli until December, said last week that the council is "off to a good start" in organizing politically, providing basic services and embracing a vision of human rights for Libya.
Cretz added the council has managed to send out the right message to the international community, such as welcoming the US, British and French air strikes that were launched 19 March to protect the Libyan people.
But Cretz said there remained legal hurdles to US recognition of a group that could one day replace Muammar Gaddafi's regime if it falls in Libya's weeks-old armed conflict. France has already recognized the TNC. Qatar followed suit Monday.
The senior US official said Washington is "still trying to develop a clearer picture, not just of the national council itself but also of the opposition military forces. But I think we're gradually developing a clearer picture."
Earlier Tuesday, British Foreign Secretary William Hague also met with Jibril, whom he had invited to London but not to the conference.
The TNC "is an important and legitimate political interlocutor and the UK is committed to strengthening our contacts with a wide range of members of the Libyan opposition who are working to create a Libya where the legitimate aspirations of its people can be met", Hague said.
The Foreign Secretary said he discussed the political and humanitarian situation in Libya with Jibril, and the importance of protecting civilians.
Meanwhile, Chris Stevens, the US special envoy to the opposition, will travel to Benghazi "sometime quite soon" to establish a "systematic channel" with groups seeking to oust Gaddafi, the US official said.
"We've had quite regular contacts with these guys over recent weeks, but there is no substitute, I think, ultimately for doing it face to face in eastern Libya," the US official said.
"Recognition is not a decision we've made at this point, but we've done a lot to increase the practical dimensions," he added.
Britain's Foreign Office confirmed opposition figures had been invited to London, but would not take part in an international meeting of 35 countries discussing Libya's future.