The U.N. envoy for Libya, Ghassan Salame, yesterday called for an immediate halt to attacks on Tripoli, hours after deadly shelling hit a residential suburb of the embattled city.

"The horrible night of random shelling of residential areas. For the sake of 3 million civilians living in Greater Tripoli, these attacks should stop. NOW!" Salame said in a tweet. At least six civilians were killed and 35 injured in the overnight rocket attack on the southern Tripoli district of Abu Salim, the head of the suburb's municipality, Abdel-Rahman al-Hamadi, said.

The bombardment came as diplomats at the U.N. Security Council began negotiations on a British-drafted resolution that would demand an immediate ceasefire in Libya. The proposed text seen by Agence France-Presse (AFP) warns that the offensive by Gen. Khalifa Haftar's Libyan National Army (LNA) "threatens the stability of Libya and prospects for a U.N.-facilitated political dialogue and a comprehensive political solution to the crisis." The military push by Haftar's LNA, which is allied to a parallel administration based in the east, marked a dangerous escalation of a power struggle that has dragged on since the overthrow of Moammar Gadhafi in 2011. Haftar, with financial and political support from certain countries, including Gulf states, has appeared as a primary actor in the war-torn country. The dispute between Benghazi and Tripoli resulted in a U.N. mediated cease-fire last year.