The head of Lebanese militant group Hezbollah, Hassan Nasrallah, has warned that his movement will "punish" Israel for the killing of a senior commander.
Hassan Lakkis was shot near his home on the outskirts of the Lebanese capital, Beirut, in early December.
"All evidence indicates that Israel is behind the assassination," Mr Nasrallah said in a televised tribute.
Israel, which fought a 34-day war with Hezbollah in 2006, denied the accusation.
Little is known publicly about Lakkis, but he was reputedly close to Mr Nasrallah and an expert in weapons manufacture.
He is said to have trained in warfare in Iran and been key in channelling Iranian assistance to Hezbollah.
In Friday's speech, the Hezbollah chief called Lakkis "one of the brilliant brains of the resistance".
"Those who killed our brothers will not know safety anywhere in the world."
Hezbollah said Lakkis was attacked outside his home in Hadath - 7km (4.3 miles) south-east of Beirut around midnight on 3 December.
Neighbours at the quiet residential complex where Lakkis lived said he arrived home alone shortly before midnight and was getting out of his car in the parking space beneath his apartment block when he was shot several times in the head at close range by attackers apparently lying in wait.
Large crowds of mourners turned out for his funeral in the town of Baalbek.
Hezbollah said Israel had tried to kill Lakkis several times previously - a claim Israel has repeatedly rejected.
"These automatic accusations are an innate reflex with Hezbollah," Israeli foreign ministry spokesman Yigal Palmor said at the time.
"They don't need evidence, they don't need facts. They just blame anything on Israel."
Hezbollah - or the Party of God - is a powerful political and military organisation in Lebanon made up mainly of Shia Muslims.
It emerged with financial backing from Iran in the early 1980s and began a struggle to drive Israeli troops from Lebanon.