Lebanon's President has asked Saad al-Hariri to stay on as a caretaker Prime Minister after his government was toppled by Hezbollah and its allies. The crisis was sparked by a dispute over the UN tribunal investigating ex-Prime Minister Rafik Hariri's murder. President Michel Suleiman has started consultations over the choice of a new premier. Mr Hariri is expected back in Beirut later on Thursday from a visit to France. Meanwhile, Lebanon's political parties are now trying to form a new governing coalition, after the resignation of 11 ministers from Hezbollah and its allies, which brought down the Hariri-led administration. The Arab League appealed for calm over Lebanon's tense security situation.