The stern of a bulk carrier operated by South Korean shipper HMM was struck by two unidentified objects on 4 May while stranded in the Strait of Hormuz, the foreign ministry said on Sunday.
A week ago, Seoul reported a blast and fire aboard the same vessel – the HMM Namu – in the strait, while anchored near the United Arab Emirates. No one was harmed in the incident.
US President Donald Trump said at the time the incident was caused by an Iranian attack.
Seoul was investigating the incident, and the vessel was towed to a port in Dubai after the blaze on Monday, with an on-site inspection conducted on Friday.
It was not certain what the objects were, though they were captured on surveillance camera, the ministry said.
Authorities said debris would be collected at the site for analysis. The objects hit the left stern at around 3.30pm on Monday, Park Il, the ministry's spokesperson said on Sunday.
The strike caused a blaze that damaged a 7-by-5-metre area, Park said, adding that the incident was unlikely to have been caused by a sea mine or any problems with the vessel's engine, generator or boiler.
"We assume the cause of the fire was irrelevant to internal issues on the ship," he said.
South Korea was in contact with relevant countries, including Iran, over the incident, Park said.
Iran has denied responsibility. It did not immediately respond to a request for comment on the objects outside of normal business hours.
An HMM spokesperson declined to comment.
Meanwhile Iran has sent its response to a US proposal to begin peace talks to end the war, the IRNA news agency reported on Sunday, as a single Qatari gas tanker was allowed to pass through the blockaded Strait of Hormuz.
The IRNA report said the response, sent to mediator Pakistan, would focus at this stage on ending the war, but no details were immediately available.
After some 48 hours of relative calm following sporadic clashes last week, hostile drones were detected over several Gulf countries on Sunday, underlining the threat still facing the region despite a month-old ceasefire.South Korean ship in Hormuz hit by unidentified objects on 4 May, ministry says
But the QatarEnergy-operated carrier Al Kharaitiyat passed safely through the strait and was heading for Pakistan's Port Qasim, according to data from shipping analytics firm Kpler, the first Qatari vessel carrying liquefied natural gas to cross the strait since the US and Israel started the war on 28 February.
Sources said earlier the transfer, which offered a modicum of relief to Pakistan after a wave of power blackouts caused by a halt to vital gas imports, had been approved by Iran to build confidence with Qatar and Pakistan, both mediators in the war.
The proposal put forward by the United States would formally end the war before the start of talks on more contentious issues, including Iran's nuclear program.