"After the Deir Ammar power station was forced to stop producing power yesterday morning (Friday) due its gasoil reserves running out, the Zahrani plant also stopped this afternoon for the same reason," Electricite du Liban said in a statement.
This led to the network's "complete collapse without any possibility of restoring it for the time being", it said.
It was the second such complete outage reported by EDL since the start of the month, after a similar incident last Saturday.
A source at the energy ministry told AFP that all was being done "to find a way out of the problem".
EDL said that a fuel oil shipment was expected to arrive on Saturday evening, and was expected to unload at the beginning of next week.
Restoring electricity is one of the many tough tasks facing Lebanon's new government, formed last month after 13 months of political wrangling.
Lebanon to suffer days of no electricity after power plants shut down
Several measures have been launched in a desperate bid to keep the lights on.
Lebanon has reached an agreement towards bringing Jordanian electricity and Egyptian gas into the country via war-torn Syria, while Shiite movement Hezbollah has separately started hydrocarbon deliveries from Iran.
The state is also bringing in some fuel oil for power stations in exchange for medical services under a swap deal with Iraq.
The international community has long demanded a complete overhaul of Lebanon's loss-making electricity sector, which has cost the government more than $40 billion since the end of the 1975-1990 civil war.