JERUSALEM - An Israeli air strike which killed four United Nations military observers at their base in Lebanon was due to an error with military maps of the area, an investigation by Israel said on Thursday.

Smoke rises from Khiam village after being hit by Israeli air strikes, one of which killed four U.N. military observers who were part of the U.N. peacekeeping mission in southern Lebanon, July 25, 2006. An Israeli air strike which killed four United Nations military observers at their base in Lebanon was due to an error with military maps of the area, an investigation by Israel said on Thursday. [Reuters]

The air strike in July destroyed a U.N. post in southern Lebanon, killing four U.N. peacekeepers from Austria, Canada, China and Finland.

Israel presented the findings of its investigation into the incident on Thursday to officials from the four countries, Israeli foreign ministry spokesman Mark Regev said.

He said maps of the area had been duplicated due to the deployment of more troops in the area.

"There was a mishap on the Israeli side where in duplication of maps, the U.N. position on the maps was not marked as it should have been and that created the tragedy," Regev said.

Israel launched an offensive into Lebanon after Lebanese Hizbollah guerrillas captured two Israeli soldiers in a cross border raid on July 12.

Regev said the investigation found that about 100 metres (yards) from the U.N. position there was a Hizbollah position where there was "hostile activity".

"Ordinance was launched on the assumption of the Hizbollah target," he said. "Had the IDF (Israeli military) known that the position targeted was a U.N. position, ordnance would never have been launched."

"There was a mistake made whereby the U.N. position did not appear clearly as it should," he said, adding the report had been passed on to U.N. investigators.

The U.N. has said it asked Israel a dozen times to stop bombing near the post in the hours before the attack.

Israel at the time expressed deep regret and said the deaths resulted from a "tragic operational mistake".

Nearly 1,200 Lebanese died, most of civilians, were killed in the 34-day war, while 157 Israelis, two-thirds of them soldiers, died.

Over 3,000 U.N. peacekeepers have already been deployed in southern Lebanon to shore up the ceasefire.

U.N. Secretary-General Kofi Annan has said Israel should complete its withdrawal from south Lebanon once 5,000 U.N. troops were on the ground.