DNA testing has confirmed that the body of a man who jihadists said they had beheaded was that of Lebanese soldier Ali Sayyed, his family said Tuesday.

Sayyed was captured along with more than 20 other members of the Lebanese security forces in the eastern town of Arsal last month.

"We've been informed by MP Khaled Zahraman that the DNA test confirmed that the body of the soldier recovered by the army is that of our martyr Ali," his uncle, Hussam al-Sayyed, told AFP.

Sayyed said that the MP, representing the family, had been told of the result by the army.

"We are very sad. We call for restraint and we do not want violent reactions," said the uncle, adding that Ali would be buried on Wednesday.

"Our only consolation will be to see the release of all the soldiers and members of the security forces who have been kidnapped," he said.

A video purporting to show Sayyed being beheaded by Islamic State (IS) jihadists emerged last week.

In the video, he is presented as a Lebanese soldier among those abducted on August 2 as clashes erupted in Arsal, which lies on the Syrian border.

IS and other jihadists overran the town of Arsal in clashes that began after the arrest of a Syrian accused of belonging to an extremist group.

Twenty soldiers, dozens of jihadists and 16 civilians were killed in the fighting that ended after mediation by Sunni Lebanese clerics.

After the truce, the militants, believed to be from the IS as well as Al-Qaeda's Syrian affiliate Al-Nusra Front, withdrew from Arsal.

But they have continued to hold 15 soldiers and 14 police taken hostage during the fighting.

The militants have reportedly sought to negotiate the release of the hostages in exchange for Islamist prisoners held in Lebanese jails.

The fighting in Arsal was the most serious border incident since the conflict in Syria began in March 2011.

Families of the remaining soldiers and police hostages have blocked roads in Lebanon in a bid to pressure the government to secure the release of their relatives.