Farm ministers from the Group of 20 major economies on Tuesday vowed to oppose any restrictive measures that would threaten food security and disrupt global food supply chains amid the coronavirus pandemic.

More than a dozen countries, including Russia, Cambodia and Thailand, have imposed export restrictions on agricultural products and other supplies as of Monday, according to the Japanese farm ministry. The restrictions center on grain.

Some countries are apparently concerned that the spread of the epidemic, which has triggered governments around the world to implement various types of lockdown measures, could affect farm production systems and cause nations to prioritize their domestic markets.

"We will guard against any unjustified restrictive measures that could lead to excessive food price volatility in international markets and threaten the food security and nutrition of large proportions of the world population, especially the most vulnerable living in environments of low food security," the G-20 agriculture ministers said in a statement following a videoconference.

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The statement also said the G-20 countries agree that emergency measures taken in the context of the current pandemic must be "targeted, proportionate, transparent, and temporary" actions that "do not create unnecessary barriers to trade or disruption to global food supply chains."

During the virtual meeting, Japanese farm minister Taku Eto said the pandemic should not be used as an excuse for countries to impose unnecessary restrictions on imports and exports, according to the Japanese Ministry of Agriculture, Forestry and Fisheries.

In Japan, imports accounted for 88 percent of domestic wheat consumption, 92 percent of soybean consumption and nearly all of the country's corn consumption in fiscal 2018. Its major suppliers include the United States, Canada and Brazil.

So far, Japan has not experienced any major disruption in food supplies, but officials are expected to continue to monitor the situation.

Among export restrictions seen worldwide, Russia has set a 7 million-ton cap on grain exports. Cambodia has banned the exports of fish and rice, and Thailand has prohibited the export of chicken eggs, according to the Japanese farm ministry.

The G-20 consists of Argentina, Australia, Brazil, Britain, Canada, China, France, Germany, India, Indonesia, Italy, Japan, Mexico, Russia, Saudi Arabia, South Africa, South Korea, Turkey, the United States and the European Union.