Hezbollah leader Hassan Nasrallah has declared the Lebanese armed group will keep fighting for Syrian President Bashar al-Assad after it spearheaded the recapture of the strategic city of Qusayr last week.

In a televised speech on Friday, Nasrallah said Hezbollah was aware of the cost of military engagement in Syria's civil war and would not be deflected from its goals.

"We will not change our position," Nasrallah said. "After Qusayr is the same as before Qusayr".

Hezbollah has become increasingly embroiled in the conflict in neighbouring Syria that is now in its third year.

"Wherever we need to be, we will be," said the Hezbollah leader during an event honouring fighters wounded in Hezbollah's military campaigns, including a 2006 war with Israel.

"What we assumed responsibility for, we will continue to be responsible for, and there is no need to give details."

The Shia Muslim movement's open military cooperation with the Assad regime to seize back Qusayr from mainly Sunni rebels has escalated tensions in Lebanon between supporters and opponents of Assad.

Damascus has said it plans to build on the victory by trying to retake large parts of the northern city of Aleppo and its surrounding province, but it is unclear whether Hezbollah will also join that operation.

"The details will depend on the requirements on the ground," Nasrallah said.

He urged his supporters to exercise restraint and maintain stability in Lebanon, after rocket fire hit both Sunni and Shia towns in the Bekaa Valley, and dozens of people were killed in street fighting in the northern city of Tripoli.

Source: Agencies