Seoul City ordered the suspension of the construction of the nation’s highest skyscraper on Monday after a fire over the weekend escalated concerns over safety, officials said.

The city directed Lotte Engineering and Construction to stop work on the Lotte World Tower in southern Seoul until an investigation into the fire is completed.

The fire erupted in the steel container of a welding machine on the 47th floor on Sunday at midnight. The fire was extinguished in 25 minutes and no causalities were reported.

“The construction will be resumed only after the cause of the fire is confirmed and safety is ensured,” said city officials. “The duration of the suspension is not decided.”

The construction below the 47th floor will be allowed for now. The construction company is probing the exact cause of the accident.

Since construction was launched in 2009, 30 percent of the work on the 123-story tower has been completed, with the main framing built up to the 62nd floor. The construction is scheduled to be finished by 2016.

While three low-rise business malls around the tower were expected to open first after the construction is finished next month, the schedule has become uncertain.

Once a company applies for approval to open, the city will conduct a comprehensive assessment on safety issues and transportation infrastructure.

“While the latest accident is not a decisive factor, it will be reflected in the comprehensive assessment,” a city official told The Korea Herald.

The construction of the 555-meter tower raised concerns over its safety following a series of accidents last year.

One construction worker was killed and five were wounded in June after part of the high-rise structure collapsed. Then in October, an iron pipe fell 50 meters from the tower while scaffolding was being removed, injuring a passing pedestrian.

Public concerns escalated over skyscrapers when a helicopter crashed into a high-rise apartment near the construction site in November and killed the two pilots.

Before the construction, the Korean Air Force also objected to the tower plan, citing the security of military aircraft flying near Seongnam airbase in Gyeonggi Province, 6 kilometers from the tower.

Despite opposition from the military, the construction plan was finally approved in 2011, after some changes in the blueprints.

By Lee Hyun-jeong (rene@heraldcorp.com)