"If there's a producer that refuses to sell the product ... and sells it at a higher price abroad ... find me the proof so it can be expropriated.''
Chavez issued the warning on his weekly broadcast programme "Hello President" after announcing a hike in milk prices by 36 per cent, a measure intended to counter recent shortages.
"If the army must be brought in, you bring in the army," he said, addressing his cabinet.
Sporadic shortages of some basic goods such as milk and chicken have been considered a political liability for Chavez ever since losing a vote last month on constitutional changes that would have let him run for re-election indefinitely.
Chavez also urged farmers to sell their milk to a newly bought state-run plant in the western state of Zulia.
The plant, bought last year for $3.7m, is being re-launched as a "socialist business" run by the state.
Chavez's government said last month that it also plans to loosen price controls on a variety of basic foods to help stem shortages.
Critics of the government blame the problem on price controls and other policies that they say discourage investment in agriculture.
The oil-producing country imports most of its food but Chavez pledged to help Venezuela boost its agricultural output in the coming years.
"We're going to turn Venezuela into a food-producing power," he said.
His comments come a day after he threatened to take control of banks that fail to meet state-imposed requirements to set aside nearly a third of all loans for agriculture, mortgages and small businesses at favourable rates.