Lebanon's top Christian cleric urged fractious politicians on Sunday to speed up the formation of a government to allow authorities to prepare for presidential elections due before the end of October.

Lebanon's Najib Mikati was nominated premier for a fourth time on Thursday after securing the support of 54 of parliament's 128 lawmakers, including the Iran-backed Shi'ite Muslim party Hezbollah, in consultations convened by President Michel Aoun.

But with splits running deep among Lebanon's ruling elite, it is widely believed Mikati will struggle to form a government, spelling political paralysis that could hamper reforms agreed with the International Monetary Fund (IMF) to unlock aid.

"Again I demand speeding up formation of a national government with the country's pressing need for it and so that the focus can immediately be on preparations to elect a president who saves the country," Maronite Patriarch Bechara Boutros Al-Rai said at a sermon on Sunday.

"We call on all parties to cooperate with the premier designate...," he added.

Analysts and politicians expect the process of forming a cabinet to be further complicated by a looming struggle over who will replace Aoun, the Hezbollah-aligned head of state, when his term ends on October 31.

This could further delay reforms needed to unlock $3 billion in IMF support needed to ease the country's financial crisis.

Now in its third year, the financial meltdown has sunk the currency by more than 90%, spread poverty, paralyzed the financial system and frozen depositors out of their savings, in Lebanon's most destabilising crisis since the 1975-90 civil war

(Writing by Suleiman Al-Khalidi; Editing by Emelia Sithole-Matarise)