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On Wednesday, an Israeli soldier directs a mechanical grabber to the site of Tuesday's firefight along the Israel-Lebanon border that killed four people. ((Ariel Schalit/Associated Press))

A tree at the centre of a deadly border firefight between Lebanese and Israeli troops was on Israeli territory, according to United Nations peacekeepers.

An Israeli soldier was attempting to cut down the tree on Tuesday near the village of Adeisseh along the Israel-Lebanon border when Lebanese forces opened fire.

A senior Israeli officer, two Lebanese soldiers and a Lebanese journalist were killed in the ensuing gun battle.

It is the most serious incident since the Israeli military and Hezbollah militant fighters fought a bloody 34-day conflict in southern Lebanon in 2006. Although Hezbollah was not involved in this week's clash, its leaders have threatened to respond if Israeli troops fire on Lebanese forces again.

Both sides have claimed the tree was in their territory.

But Naresh Bhatt, spokesman for UNIFIL, the UN peacekeeping force in the area, said in a statement the tree was located south of the UN-drawn boundary known as the Blue Line separating the countries.

Blue Line established in 2000

The Blue Line was drawn in 2000 following the end of a two-decade Israeli occupation of south Lebanon that began with a war in 1982.

Lebanon acknowledged Wednesday that the tree was south of the UN-drawn boundary, but said it viewed Israel's act as a clear provocation.

Lebanese Information Minister Tarek Mitri said his country disputes the Blue Line demarcation in certain areas, including the village where the clash took place.

Israel, which often removes trees along the border to improve the sightline into Lebanon, said the UN announcement "clearly corroborated" its version of events.

"Our routine activity yesterday was conducted entirely south of the frontier on the Israeli side and that the Lebanese army opened fire without any provocation or justification whatsoever," Israeli government spokesman Mark Regev said Wednesday.  

With files from The Associated Press