Farm prices of live pigs were raised by 1-2 baht from 56-57 baht per kg last month but the private sector pledged at a meeting with department officials on Monday not to raise retail prices for now, she said.

Bangkok Post reports that there had been rumours that retailers would raise prices by five baht per kg to cash in on holiday demand.

Pork is included among 39 product and service items on the department's price-control list. Businesses are required to inform authorities of their production costs and seek prior approval before any price increase.

Thirty-eight of the products are basic goods such as rice, cooking gas, shampoo, soap, condensed milk, fertiliser, detergent, steel and iron, with just one service: music distribution rights.

Ms Chutima said any future rise in pork prices would depend on the impact of the spread of H1N1 influenza and the cost of raw materials.

The government confirmed last week the first case of a pig contracting type-A (H1N1) influenza at a Kasetsart University research centre. The pig was believed to have caught the virus from a student at the centre.

Ms Chutima insisted the impact of the virus was minimal, as authorities have kept the spread under control.

Pig raisers nationwide have been directed to strictly monitor farm management, particularly the entry of visitors and vehicles, as a precaution to prevent the spread of the virus.

Thailand raises about 12 million pigs a year. About 70 per cent are raised on closed farms. The country last year exported about 14,000 tonnes of chilled and processed meat.