Lebanon's Sunni Muslim political heavyweights Sunday threw their support behind the ambassador to Berlin Mustapha Adib to be the next premier of their crisis-hit country.

Their choice of the relatively unknown 48-year-old diplomat came a day before parliamentary consultations were to start towards naming a new premier in the hours before a visit from France's President Emmanuel Macron.

A majority of lawmakers must decide on who to name as premier before President Michel Aoun tasks him or her with forming a new government, an often drawn out process that can take months.

A group of former prime ministers, including top Sunni political figure Saad Hariri, announced they had decided on Adib after reviewing several names.

"Those meeting agreed to name ambassador Mustapha Adib to be prime minister," said former premier Fouad Siniora in a statement, stressing the need for speedy government formation.

Lebanon's last government, headed by Hassan Diab, resigned after a massive explosion of ammonium nitrate at the capital's port on August 4 that killed at least 188 people, wounded thousands, and laid waste to large parts of central Beirut.

That disaster came off the heels of the country's worst economic crisis in decades as well as a coronavirus outbreak and widespread popular discontent with the political class.

Those who took part in mass protests from October 17 against politicians they deem corrupt and inept have already rejected any name that might emerge from the parliamentary consultations.

"We reject the outcome of parliamentary consultations, which is already known in advance and will, as usual, lead to a so-called government of national unity, one that is cooked up abroad," said Naji Abou Khalil, a member of the National Bloc opposition party that had backed the protest movement.

Adib holds a PhD in political science and taught at a Lebanese university before being named in 2013 as Lebanon's ambassador in Germany. 

He is close to former prime minister and billionaire Najib Mikati.