Part of one side of the building was smoldering as firefighters hosed it down, Reuters reported.
The building was close to completion after years of construction.
Lebanese broadcaster al-Jadeed earlier broadcast footage showing smoke billowing from the building.
Last week, a massive fire broke out at Beirut’s port and engulfed a warehouse storing engine oil, vehicle tires, and food aid.
That fire came a month after a devastating blast rocked the port, killing at least 190 people and injuring thousands of others.
