Shelves carrying salt products are left half empty at a discount store in Seo-gu, Daejeon, on Wednesday. (Yonhap)

Online transactions of salt surged by more than 800 percent in a week as Korean consumers feared the release of wastewater from the defunct Fukushima nuclear power plant into the sea could affect food safety, a recent analysis by an online tracking firm showed.

The amount of online transactions of salt products increased by 817 percent between June 7-13, compared to the same period a week earlier, according to online price comparison service provider Danawa.

Sales of salt at offline stores also surged.

Compared to the same period last year, E-mart's sales of salt from June 1 to 14 increased by 55.6 percent, while sales of sea salt jumped 118.5 percent, according to data from the nation's hypermarket chain.

At Lotte Mart, sales of salt items climbed 30 percent during the same period while those sold on online shopping mall SSG.com surged sixfold.

Amid the increased demand, salt prices surged as well.

The retail price of 5 kilograms of coarse sea salt stood at 12,942 won ($10.13) as of Thursday, 64.2 percent higher than Korea's average price for salt at 7,883 won, according to the Korea Agro-Fisheries & Food Trade Corp.

Despite the increased sales and prices, the Ministry of Oceans and Fisheries said via a press release that there are no visible signs of nationwide salt hoarding, given that there has only been an increase in consumer-level direct transactions. Such transactions make up only about 7 to 8 percent of total salt transactions across the country, according to the ministry.

"We believe that an increase in personal purchases will not affect the overall supply and demand as well as the prices of sea salt," said an official from the Fisheries Ministry.

"(However,) if transactions and prices continue to rise, we will consider holding nationwide discounts, after the government makes its own salt purchases," she added.

The ministry added that the reason for the recent rise in sea salt prices is more likely to have been because of the rainy season than the soaring demand, as the rain recently resulted in a decrease in production of sea salt.

"As the number of days of rainfall decreases and the amount of sunlight increases, production of sea salt is expected to recover to an average level starting June," the official said.

The Fisheries Ministry has sought to reassure Korean consumers that the salt and sea salt sold on the market are safe.

The government body said it has been conducting radiation tests at 10 salt fields every month since April, and so far, no radioactive substances have been detected.

"Even during the 2011 (Fukushima) nuclear accident, radioactive tests for sea salt were conducted 286 times, and even then, no radioactive substances had been detected in our sea salt," the official said.

The official added that from July to the end of the year, the government plans to expand the scope of radioactive inspection to 150 salt mines, which account for 50 percent of the nation's salt production.

Amid the panic buying, the Korea Consumer Agency issued a warning on Friday calling for caution. It said it has detected cases of sellers on e-commerce platforms using unconfirmed information to ramp up sales such as saying salt would be contaminated if the waste water from Fukushima is released.

"We issued a warning as it judged that it was an inappropriate sales act that deceived consumers with unconfirmed rumors and fake information," said an official from the Korea Consumer Agency.

The Japanese government has announced that it could start discharging contaminated water from the plant this summer. It would use filtration methods to weed out radioactive isotopes and dilute the contaminated water.

The water is expected to be released for about 30 years from 2023 to 2051.