Nabih Berri said the thousands of Lebanese and Iranian-backed Shia fighters would not depart Syria, until the country was "fully liberated from terrorists", referring to anti-regime opposition groups.
The parliament speaker told Russian state media outlet Sputnik said these forces will remain in the country until Syria "regains its territorial integrity".
He also claimed that Iranian troops and Russian forces were in Syria at the request of the government.
Syria's regime launched a ferocious assault on areas opposed to Bashar al-Assad in 2011, killing hundreds of thousands - mostly civilians - in the seven-year war.
Half the population have been made homeless due to daily regime and Russian bombing.
Berri's political party Amal is mostly Shia in composition and strongly supports the Syrian regime, and with close links to Hizballah.
Berri told Sputnik in the interview that a political solution, among international players involved in the conflict, needs to be reached to end the war in Syria.
"I believe that without negotiations between Russia, the United States, Turkey, Iran, Saudi Arabia, Egypt and at least one European country… it is impossible to resolve the Syrian crisis," he added.
"Political solution cannot be reached without agreement between these parties."
Russia and Iran's regime have helped prop up the Syrian regime, while Gulf states, the US and France have shown some support for the opposition.
When asked whether France had sought the help of Lebanon in organising regional talks on Syria, Berri said that while they "can benefit from the settlement in Syria".
He said Beirut has no "role in this topic" and will not "impose this decision".
French President Emmanuel Macron said late May that a political settlement must be reached through dialogue with Damascus, as well as opposition and regional powers interested in stability.
He also claimed in the interview that Shia militia group Hizballah had prevented IS militants reaching Lebanon.
"As for Hizballah, it is in its own country, because if it had not been for Hizballah there, Daesh would have been here," said Berri, using the Arabic acronym for the Islamic State group.
Assad's regime escalated their bombing campaign earlier in the year in an attempt to reclaim the last vestiges of rebel-held areas.
Intense shelling and ground assault followed a crippling siege, despite global calls for a ceasefire.
In April, a suspected chemical attack in Eastern Ghouta saw at least 49 people die according to medical groups and rescuers, with other estimates reaching over a hundred.
Graphic images and videos emerged on social media following Douma's alleged gas attack, showing children struggling to breathe and entire families who had succumbed to the attack on the floors of underground shelters.
The Syrian conflict began after the regime forces brutally supressed peaceful protests in 2011 that called for governmental reforms. Since then, more than half a million Syrians have been killed - mainly by Assad's forces and allies - and triggered the world's worst refugee crisis.
This article has been adapted from its original source.
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