The preliminary investigation maintains that the two-storey observer post in the town of Khiam was hit by a precision-guided missile after six hours of shelling.
Four unarmed UN observers from Austria, Canada, China and Finland, died after their UN post was hit by an Israeli air strike on Tuesday.
Ireland’s Foreign Ministry said that a senior Irish soldier working for the UN forces had warned the Israelis six times that their bombardment was endangering the lives of UN staff.
The BBC’s report on the UN probe says that each time the UN contacted Israeli forces they were assured the firing would stop.
Ireland said its most senior army officer in Lebanon had contacted the Israelis repeatedly to warn them about shelling and bombing close to UN positions prior to the fatal air strike.
An unnamed diplomat told the BBC that the report found that had Israel responded to the requests, "rather than deliberately ignoring them" the observers would still be alive.
Security Council meets
Later, the UN Security Council failed to agree on a statement condemning the killing of four UN military observers in an attack by Israel in Lebanon.
The council will restart its negotiations later today, council president and French ambassador Jean-Marc de La Sabliere said.
China had originally demanded that the statement, which is not binding, condemn the attack while the United States would not accept any criticism of its ally Israel, diplomats said.
Earlier, the Security Council was told behind closed doors that there were 21 strikes within 300 metres of the observer post during the six hours before it was completely destroyed.
Jane Holl Lute, a deputy head of UN peacekeeping operations told the Security Council that 12 of the 21 struck within 100 metres, including four which scored direct hits.
Firing continued during the rescue operation, "despite repeated requests to the Israeli Defence Forces for an abatement," she said.
Another UN base came under Israeli fire today as an artillery round fell 10 metres from its headquarters compound in Naqoura, she added.
While there was speculation Israel may have been targeting Hezbollah positions near the Khiam post, Holl Lute said there was no Hezbollah fire coming from near the outpost.
Call for joint investigation
Israeli Prime Minister Ehud Olmert has expressed "deep regrets" over the deaths.
Israel is conducting an investigation into the incident and has rejected accusations made by UN Secretary General Kofi Annan that the targeting of the UN position was "apparently deliberate".
Mr Annan has since accepted Mr Olmert’s expression of sorrow but highlighted Israel's apparent failure to heed the distress calls.
Mr Annan said he had asked Mr Olmert to agree to a joint investigation into the attack.
The UN chief said he had spoken to Mr Olmert by telephone about the Israeli air strike.
"He definitely believes it was a mistake and has undertaken to investigate and I have suggested that we have a joint investigation," Mr Annan said.
"He has expressed his deep sorrow at what happened and we accept that. But you need to look at the events of yesterday. The shelling of the UN position, which is long established and clearly marked, started early in the morning and went on until after 7:00 in the evening when we lost contact.
"Our ... people on the ground were in touch with the Israeli army trying to warn them, please be careful with our position. Many calls went out until this happened and you can imagine the anguish of the soldiers, the men and women, unarmed military observers who were down there in the service of peace."
One minute silence
Ministers attending the Rome talks, aimed at trying to find a solution to the conflict in Lebanon, held a minute's silence for the four observers.
The UN observer mission has been in southern Lebanon for 28 years.
Following the new crisis, there have been calls for a stronger international force to be sent to the region.
Britain's Foreign Secretary Margaret Beckett said she had not seen any evidence that Israel had deliberately targeted the UN position.
Asked in an interview whether she believed Israel had targeted the UN post to deter other countries from participating in an international stabilisation force, Beckett replied:
"The idea of a stabilisation force is in the long term interests of everyone in the region including Israel. They would be crazy to do anything to deliberately undermine that."
Australian observers to withdraw
Meanwhile twelve Australian soldiers attached to the United Nations peacekeeping mission in southern Lebanon are to be withdrawn.
Defence Minister Brendan Nelson said the decision to withdraw the soldiers to Beirut was due to the dangers of the ongoing war in the area.
The dozen Australian soldiers were attached to the UN Truce Supervision Organisation with which Australia has been involved since 1956.
Peacekeeping force 'suicide mission'
Foreign Minister Alexander Downer says sending a new peacekeeping force to Lebanon without a ceasefire in place would be a "suicide mission".
Speaking in Malaysia where he is attending the ASEAN forum, Mr Downer said Australia would consider taking part in any future force, but not yet.
"To go into southern Lebanon without a commitment to the withdrawal of Hezbollah and without a commitment to helping the Lebanese get back into southern Lebanon, and for the Lebanese to get control of southern Lebanon and the security situation in southern Lebanon, without that you don't have the makings of a
peace settlement.
"And it is only in the environment of a peace settlement that you can send in peacekeepers. Otherwise, of course, you are going to send them into the path of destruction."
Mr Downer said Australia would look at providing personnel when Hezbollah agreed to withdraw from the area.
Earlier this month, Dr Nelson backed participation of Australian troops in a new Middle East peacekeeping mission but today hedged on any contribution.
He said Australian troops would not be deployed under any circumstances unless the government was satisfied about the specific circumstances of the mission.
It would need to be a multinational force endorsed by the UN as part of a long-term resolution to the problem.
Meanwhile Opposition Leader Kim Beazley says any peacekeeping operation in Lebanon should be manned by troops from other countries when the war ends.
"From my point of view, the Iraq war has overstretched the Australian military, and this is probably something that someone else needs to do - step up to the mark," he said outside a union conference today.
"Europeans and other Middle Eastern states - it's more in their sphere. So that's what they ought to be doing."