Libyan border security guards at the Egypt crossing have stopped working, officials said on Wednesday, raising concern in Egypt that militants would use the border to smuggle in weapons and militants.
"The force protecting the Musaid border crossing between Egypt and Libya have withdrawn due to some problems," said a Libyan official.
Another force has been appointed to the border, without speaking out on why the previous guards left their post.
Egyptian security sources said the guards had stopped working five days ago, and added that it appears that civilians are safeguarding the border from the Libyan side.
The border is also a frequent route for migrants willing to cross over to Italy through Egypt then western Libya, with the help of people smugglers.
Libya is suffering from turmoil since the deposing and killing of Muammar Gaddafi four years ago.
Libya is currently divided into two parliaments with their own armed forces, the General National Council (GNC) in the capital of Tripoli, which was founded with the help of the United States and France following the deposal of Libyan leader Muammar Gaddafi in 2011, and the rival House of Representatives.
The House of Representatives, which has been operating from the Egyptian border town of Tobruk since June, was formed following armed uprisings by groups loyal to the renegade General Khalifa Hafter in 2014.