"Extremist militias" controlling the Libyan capital, Tripoli, were "derailing" the search for a political solution to the country's crisis, a senior United Arab Emirates (UAE) official said on Thursday.

"Abu Dhabi agreement offered opportunity to support the U.N.-led process. Meanwhile extremist militias continue to control capital and derail search for political solution," Anwar Gargash, UAE's Minister of State for Foreign Affairs, said in a Twitter post.

"Priority in Libya (is) to counter extremism/terrorism and support stability in long drawn out crisis," he added.