LG Chem Ltd, South Korea's biggest chemical manufacturer, reported a 40 percent fall in second-quarter profits, amid rising feedstock costs and weakening demand from China, its biggest market.

Net income fell to 373.9 billion won ($327 million) in the three months to June 30 from 624.5 billion won a year earlier, the Seoul-based company said on Wednesday in a regulatory filing.

The quarterly result, the smallest since it adopted international accounting rules in 2011, fell short of the 382.8 billion won average of 20 analyst estimates compiled by Bloomberg.

Sales rose 5.2 percent to 6 trillion won.