Michel Aoun, leader of Lebanon's National Patriotic Movement, has been holding meetings with Syrian officials in Damascus.
Speaking before he departing for Damascus on Wednesday, Aoun said that his visit is justified because diplomatic ties have been set up between the Lebanese and Syrian governments.
"They are welcoming me with admiration and respect ... I was a rival and the rivalry has ended and I may become a friend," he said.
Aoun said he saw no reason not to go to Syria given that Damsacus withdrew its troops from Lebanon in 2005 and that diplomatic ties between both countries were officially launched in October.
"This is a friendly and introductory visit," he said.
Aoun's move has come under fire from members of Lebanon's March 14 coalition, who accuse him of holding talks with his former adversaries purely for political gain.
A former army chief, Aoun, 73, was forced into exile after being defeated in a Syrian offensive in 1990 at the end of Lebanon's 15-year civil war.
He had declared a "war of liberation" against enemy forces.
Aoun returned in May 2005, a month after Damascus ended 29 years of military domination in Lebanon.
The pullout of Syrian security forces came after mass protests in Beirut in the wake of the assassination of Rafiq al-Hariri, a former Lebanese prime minister.
Aoun said his Lebanese foes would do better to clean up their own act rather than pointing fingers.
"In my talks ... tomorrow [today] in Syria or yesterday in Iran or any country in the world ... the issue will be Lebanon, not Michel Aoun," he said.
Aoun stunned Lebanon in 2006 when he entered an alliance with Hezbollah, a Shia Muslim group backed by Iran and Syria.
Syria and Lebanon launched diplomatic ties for the first time in October after years of tense relations following al-Hariri's murder.
Syria was widely blamed for the killing but denies involvement.
Aoun also caused a stir when he visited Iran in October and held talks with Mahmoud Ahmadinejad, the Iranian president.