Lebanon's outgoing prime minister, Hassan Diab, said on Friday that experts had found "dangerous chemicals" at a warehouse at the Zahrani oil installations in the south.
Diab said the country's atomic energy authority had identified the substances as "nuclear" after reviewing a report by German company Combi Lift, which Lebanon had tasked with clearing hazardous material at Beirut port.
A Combi Lift spokesman said they did not have any knowledge of the Zahrani issue.
"This needs to be discussed now and needs to be dealt with promptly," a statement by Lebanon's higher defence council cited Diab as saying after a meeting.
His comments came nearly eight months after a stockpile of chemicals detonated in Beirut, killing nearly 200 people in one of the largest non-nuclear explosions on record. The ammonium nitrate went up in flames last August after being stored unsafely at the port for years.
Diab's cabinet has served in a caretaker capacity since resigning over the devastation that hit much of the Lebanese capital, compounding the country's financial crisis.
After Lebanon hired Combi Lift last year in the wake of the blast, the German firm said it had found 58 containers at Beirut port that posed a threat to the city. Some of it had been there for more than a decade.
The German ambassador to Beirut, Andreas Kindl, said this month the materials in the containers were packed well but were waiting to be shipped out for disposal in Germany, as Lebanon had yet to make a $2 million payment stipulated in the contract.
Combi Lift spokesman Malte Steinhoff said on Friday the containers were still in Beirut amid talks with Lebanese authorities over financing.
"We...hope to find a solution this month," he said.