Spanish channel Libertad Digital published a video Saturday showing the moment of impact of IDF shells on a UN position in southern Lebanon, during the fighting between Israel and Hezbollah Wednesday.
A 36-year-old Spanish corporal, Francisco Javier Soria Toledo, was killed in the exchange of fire.
The video was recorded by Spanish UN peacekeepers who were sitting inside a vehicle in their military position.
They were discussing the Hezbollah attack on an IDF convoy that killed two soldiers, and the IDF response, when the shelling hits the outpost to their surprise.
Israeli Prime Minister Binyamin Netanyahu telephoned his Spanish counterpart Mariano Rajoy "to express his condolences and sadness at the death in Lebanon of Corporal Francisco Javier Soria Toledo," Rajoy's office said in a statement on Friday.
"Both leaders agreed to carry out a joint Israeli-Spanish investigation to clarify what happened and to collaborate with the investigation being carried out by the United Nations."
Toledo was part of the 10,000-strong United Nations peacekeeping force in southern Lebanon, UNIFIL, which includes 600 Spanish soldiers.
Spain's ambassador to the UN, Roman Oyarzun, blamed Israel for Soria’s death on Wednesday, several hours after the incident.
"It is clear that this was because of the escalation of the violence and it came from the Israeli side," he told reporters.
The Security Council condemned the death of the Spanish corporal. "It is clear that this was because of the escalation of the violence and it came from the Israeli side," Spanish Ambassador Roman Oyarzun told reporters, according to the AFP news agency.
The Spanish envoy said he had asked for a full investigation during an emergency meeting of the Council called by France to discuss ways to defuse tensions between Israel and Lebanon.
Condolences from Ya'alon
Israeli Defense Minister Moshe Ya'alon sent condolences to Spain's defense minister, Pedro Morenes, and to the Spanish peacekeeper's family.
He added that Israel will cooperate in investigating the incident with UNIFIL and Spanish forces. Ya'alon noted that the IDF had been responding to the Hezbollah ambush, and that the peacekeepers' post was situated in between Hezbollah forces and the IDF.
"I highly appreciate the presence of Spanish soldiers in the territory as part of the UNIFIL force, and the readiness of the government in Spain to be a partner to the effort to bring stability to the area," Ya'alon said.
Secretary General Ban Ki-moon called for "maximum calm and restraint," urging all sides to "act responsibly to prevent any escalation in an already tense regional environment," a UN statement said.
The clashes began when Hezbollah fired six anti-tank missiles at a military convoy along the border area, prompting Israel to respond with air and ground strikes.