A shortage of eco-friendly liquid solutions used in diesel vehicles in South Korea is fast raising concerns of possible disruptions in the country's supply chain.
The country requires such vehicles to install a system that reduces emissions of harmful gas.
The system requires fill-ups of diesel exhaust fluid, or DEF, which is made of urea solution.
Most of the urea used in South Korea is supplied by China. But imports have slowed since China introduced mandatory inspections of urea exports last month.
The nationwide urea shortage prompted authorities in North Jeolla Province, southwestern South Korea, to set up on Tuesday a venue to allow residents to purchase urea solutions.
Domestic media are reporting that the Chinese government has effectively limited exports of urea, as demand for coal, needed to produce the substance, has grown in the country and has affected its production.
South Korean President Moon Jae-in has stressed that the government will rely on diplomatic channels to secure urea solutions.
But some media reports are critical of the government, saying it failed to act quickly enough to deal with the issue.