Prices of coffee, cooking oil and other food items are under pressure to rise due to surging commodity prices on international markets, but domestic food manufacturers are struggling to raise prices amid persistent deflation, industry officials said Saturday.

Rising costs due to unstable weather, speculative money inflows to markets and growing demand in emerging economies may end up squeezing the profits of food makers as supermarkets and other retailers are reluctant to pass on higher costs to consumers amid fierce competition in their industry, they said.

Nisshin Oillio Group Ltd. has asked retailers to increase the price of cooking oil for home use by ¥30 per kg from this month, and last November Mitsui Sugar Co. raised the price it sells sugar at by ¥7 per gram, officials of the companies said.

The companies have been unable to raise prices as much as they want because retailers, worried that higher prices will cause their sales volume to decline, often reject price hikes.