Millers should make corn “affordable” for the Zambian population, President Michael Sata said on Monday as fears mount that high corn prices could spark food riots in the southern African country.

According to Dow Jones, the price of corn, the staple food for the nation’s 13 million people, has nearly doubled in the past couple of months, hitting around 80 Zambian kwacha ($15) a 25-kilogram bag.

This has sparked concerns across Africa’s top copper-producing nation as corn prices are a major driver of the country’s inflation.

“President Sata advised the millers to guard against exploitation of the poor people who they rely upon for their industry to thrive,” George Chellah the presidential spokesman said after a closed-door meeting between the president and the millers on Monday afternoon.

Chellah said sharp increases are not justified given Zambia has had bumper harvests in the past three seasons.

Sata said steep corn prices could trigger riots like they did in the early 1990s that culminated in the overthrow of President Kenneth Kaunda’s government.

Kaunda, also known as KK, served as the first president of Zambia, from 1964 to 1991.

He was at the forefront of the struggle for independence from European rule. He founded the Zambian African National Congress, later becoming the head of the United National Independence Party. He was the first President of the independent Zambia.

Sata rode to victory in Zambia’s 2011 elections on populist promises such as improving miners’ conditions and fighting poverty.

Industry officials attributed the steep corn prices to higher transportation and energy costs.

In the past couple of years, steep food prices have triggered riots in countries such as Uganda, Malawi, Mozambique and Sudan.

In recent years, the Zambian government has been subsidizing corn production to stabilize local prices and promote food security.

The state-run Food Reserve Agency buys the commodity at higher prices from farmers and sells it at reduced prices to millers to make it affordable to buyers.

Last year, the World Bank warned Zambia against the practice, saying that it doesn’t ensure long-term and sustainable growth of the agriculture sector.

Government officials say that millers are exporting cheap corn to neighbouring countries instead of supplying the local market.