MANILA - Jollibee Foods, Max's Group, Shakey's and Robinsons Supermarket have agreed to buy directly from garlic and onion farmers, potentially boosting their income, Agriculture Secretary Manny Pinol said.

Retail giant SM, Rustan's Supermarket, Mindanao-based NCCC Mall and ShopWise earlier pledged to source the two products straight from the farms.

Pinol said local farmers have long suffered from competition from cartels that flood the market with cheap garlic and onion, even during harvest season.

"They then buy the farmers' produce at very low prices and then jack up the prices during off-harvest season thus creating a total monopoly of the onion and garlic market," he said.

Officials of the previous administration are being investigated over their alleged involvement in garlic cartel operations.