Lebanese security officials say at least 39 people were killed in fighting on Sunday between troops and Islamic militants in the northern part of the country.
The fighting erupted with Fatah al-Islam in the city of Tripoli and the adjacent Palestinian refugee camp Nahr al-Bared. Militants also attacked an army patrol to the south.
Security officials say 22 soldiers and 17 militants were killed. There were also reports that at least six civilians were killed inside the camp.
By long-standing agreement, Lebanese police and soldiers do not enter Palestinian refugee camps.
After the fighting, Syria closed two border crossings with Lebanon because of security concerns.
Authorities say the fighting began when security forces tried to detain suspects in a bank robbery outside the refugee camp.