BEIRUT (Reuters) - Islamic State militants have beheaded a captive Lebanese soldier, images published on social media showed on Saturday, the second Lebanese soldier to be killed in captivity by the group since it raided a Lebanese border town last month.
The men were among a group of 19 soldiers missing since the attack on Arsal by militants including fighters affiliated with Islamic State. The group routinely beheads people it deems its enemies and recently killed two American journalists that way.
A caption posted with the images on a Twitter account used to publish Islamic State statements named the soldier as Abbas Medlij, identifying him as a Shi'ite Muslim.
A separate statement said Medlij was "slaughtered" after a failed escape attempt. The statement was dated Friday.
A Lebanese security source said Medlij was one of 19 soldiers missing and believed taken captive by Islamic State and other Islamist insurgents who launched the incursion into the border town of Arsal in August.
The source said the army was investigating but could not confirm that he had been killed.
Islamic State militants last week beheaded another soldier taken captive in the same incursion. After releasing a video showing the execution of Ali al-Sayyed, a Sunni Muslim, the group posted another video showing nine other soldiers begging for their lives. The militants want the release of Islamist prisoners held at a Lebanese jail.
Some of the soldiers are being held by the Nusra Front, an al Qaeda affiliate that also took part in the Arsal incursion. A number of Lebanese policemen are also being held by the militants.
The incursion marked the most serious spillover to date of the Syrian civil war into Lebanon and triggered five days of deadly battles with the Lebanese army.
Islamic State has seized swathes of territory in Iraq and Syria. The United States is assembling an alliance to fight the group in neighboring Iraq. U.S. President Barack Obama said on Friday key NATO allies stood ready to join the United States in military action to defeat the group in Iraq.
In the past two weeks, Islamic State released two videos showing the beheadings of American journalist James Foley and American-Israeli journalist Steven Sotloff, saying it was in retaliation for U.S. airstrikes against the group.
(Reporting by Tom Perry and Ali Abdelatti; Editing by Raissa Kasolowsky)