(Adds soldier killed)
BEIRUT, Aug 28 (Reuters) - Gunmen killed at least one Lebanese soldier on Thursday when they attacked an army post at the border with Syria on Thursday near a town seized by Islamist insurgents earlier this month, a security source said.
Three soldiers were wounded in the clash in the mountainous border zone just outside the town of Arsal, which was held for five days by militants, including fighters affiliated to Islamic State, in an incursion that resulted in deadly battles with the army.
The militant forces withdrew on Aug. 7, taking with them 18 captive soldiers and 15 policemen. The five-day battle marked the biggest spillover to date of the Syrian civil war into Lebanon. Dozens of people were killed, including 18 soldiers.
Overnight, the Lebanese army shelled militant positions in the same area. There was no immediate information on casualties. (Writing by Tom Perry; Editing by Angus MacSwan)