Hassan Nasrallah, leader of militant group Hezbollah, will deliver a speech on Wednesday to discuss the latest political developments in Beirut and the Middle East, the Shiite movement's Al-Manar TV channel reported.
Hezbollah sources, according to Al-Manar, have denied recent media reports about Nasrallah's deteriorating health and a trip to Iran.
"Such news is totally incorrect, and Nasrallah did not leave the country," the sources said.
Nasrallah's speech will coincide with the ongoing 23-month civil war in Syria, in which Hezbollah is accused of playing an important role.
Last Thursday, a commander of the rebel Free Syrian Army warned that his forces will target Hezbollah unless the militant group stops shelling territory held by the insurgents.
General Selim Idriss, the FSA chief of staff, told AFP on Wednesday that Hezbollah had long been taking part in hostilities in Syria, but had gone too far by shelling villages near Qusayr in the Homs province from the Bekaa valley in Lebanon.
"Hezbollah is abusing Lebanese sovereignty to shell Syrian territory and Free Syrian Army positions," said Idriss.
"In the past week... Hezbollah has been shelling into villages around Qusayr from Lebanese territory, and that we cannot accept."
The FSA had also asked the Lebanese president and premier to intervene, said Idriss, but the office of Prime Minister Najib Mikati denied any contact with the Syrian rebels.
Hezbollah has repeatedly rejected accusations that it has sent fighters into Syria.
In October 2012, however, Nasrallah admitted that members of his movement had fought Syrian rebels but said they were acting as "individuals and not under the group's direction."
A growing refugee crisis
Lebanon, where Syria still wields significant influence, is deeply divided over the Syrian revolt and fears that the sectarian civil war that has claimed nearly 70,000 lives, according to a United Nations estimate, could spill over into its smaller neighbour.
Lebanon hosts almost 300,000 Syrian refugees, a number which is growing at a rate of 3,000 a day.
Lebanese opposition leader Saad Al-Hariri predicted on Thursday the downfall of Syrian President Bashar Al-Assad, whom he accuses of planning the assassination of his father in a bomb attack in 2005.
"The regime of Bashar Al-Assad will inevitably go down. And its collapse will be loud not only in Syria but across the Arab world," Hariri said, speaking by a video link from Riyadh to mark the eighth anniversary of his father's assassination.
Last October, a deadly car bombing led to the death of almost eight people and wounded another 78 in Lebanon's Christian district of Ashrafieh, eastern Beirut. It was the most high-profile car bombing since Rafik Al-Hariri's assassination in 2005.
General Wissam Al-Hassan, a senior commander in the Lebanese Internal Security Forces, was among the dead. The incident caused a degree of deterioration in Lebanese-Syrian relations due to Al-Hassan's history of opposition to the Hezbollah-allied ruling regime in Damascus.
Al-Hassan suspected the Syrian regime of murdering Al-Hariri. The grey-moustachioed general, 47, a Sunni Muslim, had sent his wife and children to Paris because he "knew he was a target," a Lebanese opposition leader hostile to Al-Assad’s regime told AFP.
Both Saad Hariri and Walid Jumblatt, the influential Druze leader, have accused the Syrian president of being behind last year's bombing.