The approval comes after President Sisi warned UN-backed government's military against moving closer to strategic Sirte city, which is under the control of warlord Khalifa Haftar, a Cairo ally.
Egypt's Parliament has green lit a possible deployment of troops outside its borders after President Abdel Fattah el Sisi spoke of potential military operations in neighbouring Libya.
The parliament unanimously approved "the deployment of members of the Egyptian armed forces on combat missions outside Egypt's borders to defend Egyptian national security," it said in a statement
The approval comes after Sisi threatened military action against Turkey and UN-backed government's military which is moving its fighters and military vehicles closer to Sirte, a gateway to Libya's main oil terminals under the control of warlord Khalifa Haftar.
The parliamentary vote did not give details, a time frame or name Libya directly.
Trump speaks to Sisi
Shortly before the vote, Sisi and US President Donald Trump spoke by phone.
"The two leaders affirmed the need for immediate de-escalation in Libya, including through a ceasefire and progress on economic and political negotiations," the White House said in a statement.
Trump also told French President Emmanuel Macron by phone that the conflict "has been exacerbated by the presence of foreign forces and arms," the White House said.
UN spokesman Stephane Dujarric told reporters: "There is no military solution to the current crisis in Libya and there must be an immediate ceasefire."
The UN-backed Libyan government's forces have moved closer to the central city of Sirte, which they seek to recapture from Haftar's illegal militia.
Backers of warring sides
The move could bring Egypt and Turkey, close US allies that support rival sides in Libya’s chaotic proxy war, into direct confrontation.
Sisi has called the strategic coastal city of Sirte a "red line" and warned that any attack on the town would prompt Cairo to intervene militarily to protect its western border with the oil-rich country.
The last time Egypt sent ground troops abroad for combat was in 1991 in Kuwait as part of a US-led coalition to drive out Iraqi troops.
Egypt backs eastern-based Haftar's illegal militia while Turkey supports fighters allied with the UN-supported government in Tripoli, in the west.
Egypt has flown air strikes on the UN-supported government in Libya since the toppling of Muammar Gaddafi in 2011 plunged the oil producer into chaos.
Along with Egypt, Warlord Haftar is also backed by the United Arab Emirates and Russia, while in addition to Turkey, the Tripoli forces are aided by Qatar and Italy.
Battle for Sirte
Warlord Haftar's militias launched an offensive to take Tripoli from the UN-supported government in April last year but their campaign, which had stalemated after reaching the outskirts of the Libyan capital, suffered a blow last month when the Tripoli-allied forces, with Turkish support, pushed them back and gained the upper hand in the fighting.
The Tripoli government retook the capital's airport, all main entrance and exit points to the city and a string of key towns in the region.
It pushed on eastward, vowing to also retake Sirte, which Haftar captured earlier this year. Both sides have been mobilising for weeks.
Capturing the city would open the door for the Libyan government forces to advance even farther eastward and potentially take vital oil installations, terminals and fields now under Haftar's illegal control.