A Saudi man was kidnapped on Sunday near the Lebanese city of Baalbek in the Beqaa Valley after reportedly being lured to the country to buy property.
A judicial official told AFP that Lebanese authorities had launched an investigation into the disappearance of the man, who is believed to be in the Al Sharawneh neighbourhood on the outskirts of Baalbek.
The Lebanese army searched the area and seized weapons and ammunition on Monday.
A ransom demand has not been received but the Saudi man was likely to have been taken "with the aim of financially extorting" him, the judicial official said.
Baalbek is often the scene of fighting between rival clans and the army frequently carries out raids over cases of drug trafficking, theft, kidnapping and other crimes.
Hezbollah, the political party and armed group that is backed by Saudi Arabia's regional rival Iran, is powerful in the area.
A devastating economic crisis that first became apparent in 2019 has plunged much of Lebanon into poverty, with widespread shortages of bread, electricity, water, medicines and other essentials.
In April, a gang kidnapped an Egyptian accountant in Baalbek. He was rescued by the army after two weeks in captivity.
The kidnapping comes three months after Saudi Arabia announced the return of its ambassador to Lebanon following a diplomatic crisis last year between Lebanon and Arab states in the Gulf.
Saudi Arabia was one of four Arab states that withdrew their ambassadors from Lebanon in October last year after comments by George Kordahi, who was Lebanon’s information minister, about the Saudi-led Arab coalition's intervention in Yemen. The four Arab states also asked their citizens to return home.
Mr Kordahi resigned as a result of the falling out.
Along with withdrawing its ambassador, Saudi Arabia accused Hezbollah of turning Lebanon into “a launching pad for implementing projects of countries that do not wish well for Lebanon and its brotherly people".
Riyadh also suspended fruit and vegetable imports from Lebanon in April last year, saying shipments were used for drug smuggling and accusing Beirut of inaction.