The mother of a Lebanese soldier held captive by the militant Islamic State group says that photographs posted online purporting to show his beheading appear real.

Zeinab Noun called her son, Abbas Medlej, a "martyr" after Islamic State supporters posted images Saturday appearing to show a captured Lebanese soldier before and after he was beheaded.

Medlej's maternal uncle, Abu Ali Noun, also said the photographs appeared to be of his nephew.

A spokesman for Lebanon's military said it was still investigating the incident.

Militants from the Islamic State and other groups in Syria are holding around 35 Lebanese soldiers and policemen captive. They were seized in August when militants from Syria overran the Lebanese border town of Arsal in the most serious spillover of the neighboring civil war.