The Lebanese government has decided to ask the United Nations to extend the mandate of an ongoing inquiry into the killing of Rafiq al-Hariri, the former prime minister. Official sources said the cabinet passed the decision at an emergency session on Tuesday to ask for a one-year extension. The mandate of the 11-month inquiry expires on June 15 but the investigation has run into difficulties, partly due to Syrian reluctance to cooperate and disputes over the veracity of witness statements.The 15-member Security Council had already extended the mandate of the inquiry for six months in mid-December following an earlier request from the Lebanese government.