Hezbollah chief Hassan Nasrallah on Friday said his Lebanese Shiite movement would boost its support for Syria's regime after one of its top commanders was killed there last week.

"We will increase and bolster our presence in Syria," Nasrallah said in a speech during a ceremony to mark a week since Mustafa Badreddine was killed in an artillery attack near Damascus.

"More commanders than before will go to Syria. We will be present in different ways and we will continue the fight," he said.

According to Hezbollah expert Waddah Charara, the Shiite militant group has sent between 5,000 and 6,000 combatants to Syria since 2013.

Between 1,000 and 2,000 Hezbollah fighters have been killed in fighting there, other experts say.

"Our revenge will be great and final defeat on these terrorist, takfiri (Sunni extremist) and criminal groups," said Nasrallah.

Hezbollah has accused Islamist extremists of killing Badreddine, but did not name any single group.

Badreddine was on a US terror sanctions blacklist, was a key suspect in the 2005 assassination in Beirut of Lebanese ex-premier Rafiq Hariri and was one of the "most wanted" by Israel.

But Nasrallah said no evidence pointed to Israel -- the Shiite movement's sworn enemy -- being involved in the killing.

"We reviewed Israeli flight patterns and movements and of course what we found on the site of the explosion," he said.

"We have no sign or proof leading us to the Israelis."

Nasrallah paid tribute to Badreddine, who he said "was one of the first to join the resistance in its beginnings" after it was founded in 1982 with help from Iran's Revolutionary Guard.

After climbing up the ranks, Badreddine took on "main military responsibilities" at Hezbollah between 1995 and 1999, he said.

"When Hezbollah decided to enter Syria, the commander was given the responsibility to lead Hezbollah's military and security units in Syria," he said.

Badreddine was killed in an area technically under the control of the Syrian army while Hezbollah and Iranian fighters are also present there.

The closest rebel positions were seven kilometres (four miles) away in the Eastern Ghouta area.

Syria's war has killed at least 270,000 people and displaced millions since it erupted with anti-government protests in 2011.
Source :AFP