While trade restrictions can be effective in the short term, Tung Duc Phung, the director of the Mekong Development Research Institute in Hanoi, said they can harm the supply side in the long term and even slow economic growth.

"The most important measures these countries need (are) to promote the expanding of agriculture by supporting policies to attract more investment," Phung told China Daily.

Marcel Schroder, an economist at the Asian Development Bank, notes the worrisome trend of increased trade restrictions around the world. Since the beginning of the Ukraine crisis, more than 50 instances of trade restrictions have been introduced globally, meaning that export and import controls now apply to more than 20 percent of world trade, Schroder said.

"These measures have worsened price pressures in agricultural commodities markets, which in turn may trigger a vicious cycle of more trade restrictions over food supply concerns by other countries and further price increases," Schroder said.

Russia and Ukraine are also key exporters of sunflower oil and barley, contributing more than three-fourths and one-third of supplies to international markets, respectively. In addition, Russia is the world's biggest exporter of fertilizers. But production of those commodities in the two countries, along with exports, has largely come to a halt.

The Kremlin said on May 23 that Russia is not the cause of the food supply problems. Rather, those countries that have imposed sanctions against it are to blame, for the effects of those measures.

United Nations Secretary-General Antonio Guterres warned that tens of millions of people may suffer in a looming crisis that could last years.

"In the past year, global food prices have risen by nearly one-third, fertilizer by more than half, and oil prices by almost two-thirds," said Guterres, noting most developing countries lack the fiscal space to cushion the blow of these huge increases.