It could take more than a year to restore parts of a historic wall in Seoul that collapsed during heavy downpours earlier this week, according to an official handling the restoration efforts.

On Tuesday morning, a passerby reported seeing a collapsed portion of the northern wall of Hanyangdoseong, also known as the Seoul City Wall, to the Jongno-gu office, which then relayed the discovery to the Korea Heritage Service, according to the state agency.

Damage to the wall spans 30 meters, and no casualties have been reported.

“The damage isn’t light, and we definitely cannot put everything back by this year. By the first half of next year is also tricky,” said an official at the Korea Heritage Service.

“The agency needs to approve the restoration plan before the city can bring in workers to repair the parts affected,” the official added.

Built to defend Seoul against foreign invaders during the Joseon Era (1392-1910), the wall encircles key areas in the capital, including the five Joseon-era palaces, and is under review for a UNESCO World Heritage Site listing. It measures 18.6 kilometers in length and has an average height of 5-8 meters.

In September last year, the KHS applied for a UNESCO preliminary assessment -- the first step of the four-stage procedure that determines which historic sites earn a World Heritage Site designation.