Egypt's parliament authorized the deployment of troops outside the country on Monday after the president threatened military action against Turkish-backed forces 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 ... against criminal armed militias and foreign terrorist elements", it said in a statement.
The deployment would be made on a "western front" - a likely reference to western neighbour Libya. The move could bring Egypt and Turkey - which support rival sides in Libya's chaotic proxy war - into direct confrontation.
Egypt's House of Representatives, packed with supporters of President Abdel Fattah el-Sisi, approved the plan after a closed-door session where deputies discussed "threats faced by the state" from the west, where Egypt shares a porous desert border with war-torn Libya.
Stephanie Williams, acting head of the UN support mission in Libya, on Monday called for an "immediate ceasefire ... to spare the 125,000 civilians who remain in harm's way and for an end to the blatant violations of the UN arms embargo".
Her comments came following her meeting on Sunday with the president of neighbouring Algeria, Abdelmadjid Tebboune.
Turkey, meanwhile, demanded an "immediate" end to the support for rebel commander Khalifa Haftar in Libya after trilateral talks held in Ankara between Libyan, Turkish, and Maltese officials on Monday.
"It is essential that all kind of help and support given to putschist Haftar - which prohibits ensuring Libya's peace, tranquillity, security, and territorial integrity - ends immediately," Turkish Defence Minister Hulusi Akar said.
Haftar's backers should "stop supporting an unrealistic and wrong project", the UN-recognised Government of National Accord's (GNA) Interior Minister Fathi Bashaga said.
Egypt, the United Arab Emirates, and Russia have been backing Haftar's eastern-based forces in the conflict, while Turkey supports the GNA.
Egypt's president warned in June that any attack on Sirte or the inland al-Jufra airbase would prompt Cairo to intervene militarily, purportedly to protect its western border with Libya.
The GNA denounced Egypt's threat of military intervention in the North African nation, labelling it a "declaration of war".
Qatar's state minister for defence affairs met on Monday with the Turkish defence minister and Libya's minister of interior to discuss the latest developments in Libya, Qatar's defence ministry said.
Sirte lies 800km (500 miles) from the Egyptian border with Libya's most important crude export terminals in between.
Cairo sees the city as a "red line" and has called for talks between Libya's rival factions. Ankara and the GNA have called on Haftar to withdraw from the city and negotiate a ceasefire.