Iranian-backed Lebanese group Hezbollah's chief Hassan Nasrallah has said it will respond to the killing of leader Fuad Shukr by Israel last week.

Speaking in a televised speech to mark one week since Fuad Shukr’s killing, Hassan Nasrallah said the retaliation would be “strong” and “effective”, and that the assassination could not be treated as an ordinary attack, BBC reported.

Hassan Nasrallah warned that the group might act alone or work in coordination with Iranian-supported factions in the region.

His announcement came at a time when there is fear of further escalation of tension between Hezbollah and Israel.

Several nations, including the US, have directed its nationals to leave Lebanon.

Meanwhile, at least 19 people were injured after a drone attack was conducted by Hezbollah on the Western Galilee region of Israel.

The Israel Defense Forces recently said Hezbollah's most senior military commander Fuad Shukr "Sayyid Muhsan" was killed during a rare strike carried out in Beirut city.

"Fuad served as Hezbollah Secretary-General Hassan Nasrallah's right-hand man and was Nasrallah's adviser for planning and directing wartime operations," IDF said in a statement.

IDF said Fuad Shukr has directed Hezbollah's attacks on Israel since October 8th, and he was the commander responsible for the murder of the 12 children in Majdal Shams in northern Israel on recently, as well as the killing of numerous Israelis and foreign nationals over the years.

Fuad joined the Hezbollah terrorist organization in 1985 and has since held a number of senior positions.

As part of his role, he was a member of the Jihad Council - Hezbollah's most senior military forum.

In the 1990s, Fuad advanced numerous attacks against the IDF and the South Lebanon Army.