Syria's state-run news agency, SANA, reported that 17 Lebanese "gunmen" were killed inside Syria last week, and on Sunday, Syrian TV aired footage of the dead.
Bassam al-Dada, a political adviser for the rebel Free Syrian Army, said the group believes the Lebanese men were the victims of a "complicated Syrian intelligence operation" aimed at showing that foreign fighters are involved in fighting in Syria.
According to their relatives, Malek Haj Deeb and Bilal al-Ghoul left their parents' homes a week ago saying they were going to downtown Tripoli. Hours later, the families grew concerned and started calling the men's mobile phones.
There was no sign of them until two days later, when local media reported that a group of Lebanese citizens had been killed while fighting in Syria.
Pictures of the men, shown to the AP by their families, showed them clean-shaven and playing in the snow in one of Lebanon's mountain towns, and in front of Tripoli's Crusader-built citadel.
"We want their bodies back," Omar al-Ghoul said.
On Wednesday, Syrian Ambassador Ali Abdul-Karim Ali told Lebanese Foreign Minister Adnan Mansour that Damascus has agreed to repatriate the men's bodies. Lebanon's National News Agency said the countries would soon discuss how to hand them over.
Members of the International Committee of the Red Cross visited the dead men's families on Tuesday and took details about the men, their brothers said.
Jihad Haj Deeb said his brother was about to resume his college studies and would not have jeopardized his future to fight in Syria.
"He registered at the university four days before he went missing," Haj Deeb said, adding that his brother took 500,000 pounds ($335) from their father to pay his tuition at Lebanese University, where he was a third-year mathematics student. Haj Deeb's father, a school bus driver, makes $400 a month and has nine other children.
"Had he been planning to go to Syria, he wouldn't have registered," added Jihad, saying his father had to borrow the money.
Meanwhile, the unrest inside Syria shows no sign of slowing down.
The uprising began with peaceful protests in March 2011 and later escalated into a civil war that the opposition says has killed more than 40,000 people.
Besides the violence roiling the capital, Damascus, there was growing speculation about the fate of a top Syrian spokesman who has become a prominent face of the regime.
Lebanese security officials have said Foreign Ministry spokesman Jihad Makdissi flew Monday from Beirut to London. But it was not clear whether Makdissi had defected, quit his post or been forced out. Syria has had no official comment on Makdissi, who has defended the regime's crackdown on dissent.
Associated Press writers Karl Ritter in Doha, Qatar, Suzan Fraser in Ankara, Turkey, and Jamal Halaby in Amman, Jordan, contributed to this report.