Sainsbury's is more than doubling the number of biscuit lines in its own-­label range made with ­sustainable palm oil.

The retailer is converting 17 SKUs in its line-up by the end of July, increasing the number of sustainable palm oil-based biscuit lines in its portfolio to 28.

It first made the switch to sustainable palm oil with its rich tea and digestive biscuits in 2008 as part of its goal to use only sustainable-certified palm oil across its entire own-label range by the end of 2014.

Sainsbury's said it would now be turning its attention to the rest of its own-label biscuit portfolio.