BEIRUT (Reuters) -Lebanese politician Saad al-Hariri abandoned his effort to form a new government on Thursday, saying it was clear he would not be able to reach an agreement with President Michel Aoun, plunging the country deeper into crisis.

       Lebanon is suffering an economic depression the World Bank has described as one of the most severe in modern history. Its currency has lost more than 90% of its value in less than two years, leading to spiraling poverty and crippling shortages.

       "It is clear we will not be able to agree with his Excellency the president," Hariri told reporters after meeting Aoun for barely 20 minutes. "That is why I excuse myself from government formation."

       With no obvious alternative for the post, which must be filled by a Sunni Muslim in Lebanon's sectarian system, there is little hope of a government that can start fixing the economic situation.

       Hariri said Aoun had requested fundamental changes to a cabinet line-up he had presented to him on Wednesday. Aoun had told Hariri that they would not be able to agree, Hariri said.

       There was no immediate comment from the presidency.

       Hariri was designated to form the new government in October, after the resignation of Prime Minister Hassan Diab in the aftermath of the Aug. 4 Beirut port explosion. Diab continues in a caretaker capacity.

       (Reporting By Beirut Bureau, writing by Maha El Dahan; Editing by Toby Chopra and Philippa Fletcher)