This is seen as a knock-on effect from the Cabinet-approved sugar price increase last month of Bt3 a kilogram ex-factory after a 22-year freeze.

The move raising the shelf price of sugar to Bt17.50 a kilogram.

A ministry official said leading manufacturers had been urging higher prices since September and Coca-Cola and Pepsi had asked for an increase of Bt1.25-Bt2, which the ministry had rejected for fear of adding to inflation.

Soft drinks are one of 37 products currently controlled by the Internal Trade Department.

"We now consider the time ripe for a price increase in view of higher manufacturing costs generated by oil and sugar prices," the official said, adding that the increase should have little effect on consumers, who would readily understand the manufacturers' plight.

A manufacturers' report says 33 per cent of their income goes in tax and of the rise in cost of Bt3.57 a litre in the last year Bt2.74 was accounted for by raw materials, tax and management and Bt0.83 by labour and fuel.

Petchanet Pratruangkrai, The Nation