In a statement, IRP said its board of directors "reviewed the group's business prospects and decided to take measures to further improve its cost competitiveness and also improve its market share in its home market - Thailand".

Under the investment plan, the output of its amorphous PET polymers plant in Lop Buri will rise to 180,000 tonnes per annum in the third quarter of 2008, which will meet total captive requirement for production at the plant.

The plant will benefit from economies of scale and will be the largest producer in Thailand, the company said.

To finance the expansion, IRP needs only US$15 million (Bt570 million) due to the availability of existing infrastructure. Operating expenditure is expected to increase only by the variable component because of the existing infrastructure, thereby improving the group's overall cost structure.

"Thailand is the ideal location for IRP to expand because of surplus availability of primary raw materials and also because the group's in-house consumption of PET is steadily growing at its joint venture Petform," IRP said.

IRP said the global demand for PET polymers was around 12 million tonnes and continued to grow by 8 to 9 per cent per annum, equivalent to around one million tonnes. The growth in demand is coming from existing and new applications in soft drinks, water, iced tea, juices, energy drinks and other beverages.

IRP said its plant in Lithuania, which started production at the end of October 2006, was now operating at full capacity. It said product quality and specifications had been well accepted by customers and the plant had been successful in servicing the European market, where demand is around 3.5 million tonnes per annum.

IRP said its plant in North Carolina, in the US, would almost double its capacity from 116,000 to 225,000 tonnes per annum by the end of this month.

"IRP has the largest market share of PET polymers in Thailand and will be the leading manufacturer of PET polymers in the world on completion of announced projects and expansions in the US and Thailand," the company said.