Israeli Prime Minister Benjamin Netanyahu vowed "harsh action" on Monday against a soldier caught on camera vandalising a statue of Jesus Christ in southern Lebanon.

The photo, which the military determined was authentic after it spread online, shows an Israeli soldier using a sledgehammer to strike the head of a statue of a crucified Jesus that had fallen off a cross.

The sculpture is located in the Christian village of Debl in south Lebanon, near the border with Israel, the local municipality told AFP, but officials could not say whether it had been damaged. AFP is currently unable to access the village.

"I was stunned and saddened to learn that an IDF soldier damaged a Catholic religious icon in southern Lebanon," Netanyahu wrote on X.

"I condemn the act in the strongest terms. Military authorities are conducting a criminal probe of the matter and will take appropriately harsh disciplinary action against the offender," he added.

Israel has conducted airstrikes across Lebanon and invaded the country's south after Hezbollah entered the Middle East war in support of its backer Iran on March 2. 

The fighting killed nearly 2,300 people and displaced more than a million before a ceasefire came into effect last week. Israel has lost 15 soldiers in the war.

The military said it had determined after an investigation that the image circulating on social media was genuine and showed an Israeli soldier operating in southern Lebanon.

It said in a post on its official X account that it viewed the incident with "great severity", adding that the "soldier's conduct is wholly inconsistent with the values expected of its troops".

The army said "appropriate measures will be taken against those involved" but did not go into further detail.

It said it is working with the community to "restore the statue to its place".

Adeeb Joudeh AlHusseini, the custodian of the keys of the Church of the Holy Sepulchre in Jerusalem, condemned the incident in a statement.

"This is not a passing incident, it is a direct violation of a sanctity that goes beyond stone and wood to strike at the dignity of faith itself," AlHusseini said.

The act exposes "the fragility of rhetoric that claims respect for religions while practices on the ground contradict it", he added, calling for a "clear and unequivocal stance that puts an end to any violation of sacred sites".

Israeli Foreign Minister Gideon Saar also condemned the "shameful and disgraceful" conduct.

"I am confident that necessary severe measures will be taken against whoever committed this ugly act," he wrote on X.

"We apologise for this incident and to every Christian whose feelings were hurt."

Israeli troops remain in southern Lebanon despite the ceasefire.