At least three people have been hurt in clashes between police and protesters outside the Egyptian embassy in Beirut.
About 200 people gathered to demonstrate against Egypt’s building of an underground wall along its border with Gaza.
Authorities say the aim of the 14-kilometre barrier is to stop the smuggling of arms. But critics say it will put further strain on Gaza, where people have to smuggle in basic goods.
Hundreds of underground tunnels are said to link Egypt with Gaza, which is under an Israeli-Egyptian blockade.
The territory has been isolated ever since the Islamist group Hamas took control in 2007.