An Israeli officer and several Lebanese soldiers were killed in the exchange of fire Tuesday across the volatile border.

"The U.N. announcement today clearly corroborates the Israeli version of events," said Mark Regev, an Israeli government spokesman in a written statement. "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 what-so-ever."

UNIFIL said, "The investigations are still ongoing" and the findings will be released after they conclude.Lt. Col. Dov Harari, an Israeli battalion commander, was killed in the fighting, according to an Israel Defense Forces statement. Another Israeli soldier was seriously wounded, it said.

A Lebanese army spokesman said at least two Lebanese soldiers were killed and several others were wounded.

Lebanon's official National News Agency reported that journalist Assaf Abu Rahal also was killed in the exchange of fire between Lebanese and Israeli soldiers.

Israel filed a letter of complaint with the U.N. secretary-general and the U.N. Security Council Tuesday after the incident.

"These attacks threaten stability, peace, and security in our region," Israeli Ambassador Danny Carmon said in a letter to Secretary-General Ban Ki-moon, asking that the United Nations address the matter.

"In response to this grave incident that constitutes a blatant violation of U.N. Security Council resolution 1701, Israel exercised its right of self-defense, responding with the appropriate measures on LAF (Lebanese Armed Forces) positions in the area."

Two separate narratives emerged in the aftermath of the incident, highlighting the tensions along the Israel-Lebanon border.

Israel said the Lebanese fired on Israeli soldiers who were on the Israeli side of the border.

In Jerusalem, Israeli Intelligence Minister Dan Meridor said the incident was captured on video and that it all occurred on Israeli soil.

"This is all under Israeli sovereignty," he said. "Somebody wanted to ignite fire and kill one of our soldiers and wound another. We responded in a military way. But this should serve as a warning: Don't dare do this again."

Israeli Defense Minister Ehud Barak warned the Lebanese government against continuing provocations of Israeli forces and demanded an investigation into Tuesday's violence. He said Israel would not tolerate attacks on Israeli territory.

"The IDF will continue to act firmly and determinedly to protect the residents of Israel and the sovereign borders of Israel," Barak said in a written statement.

The Israeli military said its soldiers were on "routine activity" when the incident occurred. It issued a statement saying that the soldiers were in "an area that lies between the 'blue line' [the internationally recognized border between Israel and Lebanon] and the security fence, thus within Israeli territory."

The Lebanese army's account and a report from Lebanese media said, however, that the hostilities occurred when Israel wanted to remove a tree.

A Lebanese army unit stopped the Israelis, and the U.N. Interim Force in Lebanon intervened, the National News Agency said.

The Lebanese army said it asked the U.N. force to arbitrate the issue, but the Israeli forces didn't comply and entered Lebanese territory. That led the Lebanese army to open fire, with Israeli forces returning artillery fire and hitting a house in the village of Odaise.

Lebanese President Michel Suleiman said Israel violated U.N. Resolution 1701 in crossing the blue line and by bombing a Lebanese army checkpoint in Odaise. He said Israeli aggression needs "to be confronted, whatever the sacrifices are" and that he will pursue the issue diplomatically.

Israel fought a five-week war with Hezbollah in the summer of 2006 after Lebanese-based militants kidnapped two Israeli soldiers during a cross-border raid.

Resolution 1701, which was intended to resolve the 2006 conflict, bars Israel from conducting military operations in Lebanon. Israel has accused Lebanon-based Hezbollah, considered a terrorist group by the United States, of violating the resolution by smuggling arms into southern Lebanon.

In a televised speech marking the fourth anniversary of the summer war, Hezbollah Secretary General Hassan Nasrallah accused Israel of never having stopped its attacks on Lebanon and said it is guilty of 7,000 violations of Resolution 1701.

"We salute the Lebanese army and we salute their commander, their soldiers and their officers for baptizing the land with their blood," Nasrallah said. "Our young men were in Odaise and other neighboring villages in the south but we asked them to exercise restraint. We were ready to fight and defend our land."

In the aftermath of the 2006 fighting, the United Nations deployed peacekeepers to the area. The U.N. troops were focused Tuesday on restoring calm, said spokesman Neeraj Singh.

Acting Commander Brig. Gen. Santi Bonfanti flew to Odaise and said the situation had quieted. The United Nations was urging Israel and Lebanon "to exercise maximum restraint," Singh said.

Lebanese Prime Minister Saad Hariri discussed the potentially explosive situation with Egyptian President Hosni Mubarak, Jordanian Prime Minister Samir Rifai, Arab League Secretary General Amr Moussa and Turkish Foreign Minister Ahmet Davutoglu, Hariri's office said.

Meanwhile, Syrian President Bashar al-Assad stated Syria's support for Lebanon "against the heinous aggression launched by Israel," according to the Syrian state-run news agency SANA.

"This aggression proves once more," he said, "that Israel has always been seeking to destabilize security and stability in Lebanon and the region."

In Washington, the Obama administration expressed concern about the clashes and urged both sides to exert calm while the United Nations investigates.

State Department Spokesman P.J. Crowley told reporters the State Department was in touch with the Israelis, Lebanese and the United Nations mission on the ground to establish the facts.

But Hezbollah leader Nasrallah predicted any U.N. investigation would not favor Lebanon.

"Israel wasn't condemned for massacres that they have committed," he said. "The U.N. will not condemn their aggression in Odaise."

Still, he predicted, the incident is not likely to turn into another war. "I don't believe that there is a likelihood of a[nything] close to war but there is reason for concern," he said.