Washington (AFP) - European powers and the United States welcomed renewed dialogue between Libya's rival political factions, amid UN-mediated talks aimed at reaching an agreement to form a unity government in the strife-torn country.In a joint statement, France, Germany, Italy, Spain, Britain and the United States urged the participants in the talks to "enter into the discussions constructively and in good faith in order to reach agreement on a national unity government and arrangements for a ceasefire as quickly as possible.""We call on the Libyan political leaderships to act responsibly and to make clear their support for the dialogue and call on them to exercise authority over military and militia leaders and ensure civilian oversight and control of their actions and disavow military actions not taken in that framework," they added.As the talks got under way in Morocco, the internationally recognized government said loyalist forces had launched an offensive to "liberate" Tripoli, seized by Islamist-backed militia last summer."We are deeply concerned about the growing threat from terrorist groups in Libya, including Da'esh, who have expanded their presence in Libya as a result of the absence of a strong, united, central government in the country," the world powers said, using an Arabic acronym for the IS group."The United Nations-led process to establish a national unity government provides the best hope for Libyans to address this terrorist threat and to confront the violence and instability that impedes Libya's political transition and development."Libya has been wracked by violence since the NATO-backed uprising that toppled longtime dictator Moamer Kadhafi in 2011, with rival militias and administrations battling for power.Join the conversation about this story Click here to read full news..