Egypt will not stand idle in the face of any moves that pose a direct threat to Egyptian and Libyan national security, President Abdel-Fattah al-Sisi said on Thursday, according to a presidency statement.

The statement also said tribal leaders meeting Sisi in Cairo had authorized the president and Egypt's army to intervene in their country "to protect Libyan sovereignty".

The tribesmen are allied to eastern Libyan commander Khalifa Haftar. Egypt borders Libya to the west.