British Polythene Industries (BPI) expects to report an improved half-year performance boosted by lower costs and "resilient" sales in the agricultural sector.

The Greenock company – which makes agricultural films, packaging for goods across a range of sectors and also recycles polythene film – had previously signalled trading was going well but now anticipates it will be "comfortably" ahead of its 2012 results.

BPI, headed by John Langlands, said: "This underpins our confidence in current market expectations for the full year."

For the six months ended June 30, 2012, BPI recorded turnover of £273.1 million and pre-tax profit of £13.3m.

Underlying pre-tax profits across the whole of 2012 were up 7% to £20.4m in spite of lower turnover of £479m.

BPI, which employs 350 people across its Scottish operations in Ardeer in North Ayrshire, Greenock and Dumfries, said the improvements in 2013 had come in spite of a slow start to the year and a colder than normal spring.

Sales in the agricultural sector had offset lower volumes in other products.

Overall volumes are expected to be similar to those seen in the first half of 2012 which came in just short of 150,000 tonnes.

BPI confirmed raw material costs has dipped in April and May but risen again in June.

However it did not see the upward trend continuing for long, suggesting it was "unlikely" the demand in the market would support higher prices.

Analysts at Investec kept a buy rating on the BPI stock.

Shares ended the day unchanged at 545p.