During the visit to the Libyan capital, British Foreign Secretary William Hague on Monday held talks with Libyan interim leader Mustafa Abdel Jalil, re-opened the British embassy and announced the appointment of John Jenkins as new ambassador to Libya

"It is important for the militias to be integrated into the work of the National Transitional Council (NTC), and then of course into the national transitional government that will be formed once the liberation of the country is declared," Hague told journalists in Tripoli.

There are dozens of different militias, or brigades, in the Libyan capital alone, some of which have shown themselves reluctant to take orders from the NTC leadership, although so far any disagreements have been peacefully resolved.

Hague said the task of bringing together "so many different groups" that contributed to the revolution was a key challenge for Libya's new government. He was speaking as some of those groups encountered fierce resistance in the two remaining strongholds of Gaddafi loyalists -- in the ousted strongman's hometown of Sirte and in the desert town on Bani Walid, south of Tripoli.

But Britain's top diplomat said the world had consistently underestimated the NTC, which continued to make progress, and pledged Britain's ongoing support, including 20 million pounds ($32 million) for Libya's stabilisation fund and another 20 million pounds to support political and economic reform.

Hague said Britain would provide healthcare for up to 50 Libyans badly injured in the conflict, and would invite health experts to observe their treatment, so that they could support the patients on their return to Libya.

Britain played a major role in the NATO campaign in Libya and its Royal Air Force planes are still bombing the remnants of Gaddafi's forces.