A leading food manufacturer says it will switch to a "sustainable" source of palm oil for its most famous brands, such as McVitie's, Jaffa Cakes and Penguin.

United Biscuits said that by mid-2010 it hopes that two-thirds of its palm oil will come from sources certified as sustainable. It hopes that 100 per cent of its oil will come from sustainable sources by the end of 2011.

Palm oil is an ingredient of a wide variety of packaged foods and is one of the main causes of rainforest destruction. However, it is usually labelled as "vegetable oil" or "vegetable fat" and many consumers do not realise the product has helped to destroy a rainforest.

Palm oil plantations have taken land from indigenous peoples, exacerbated emissions of carbon dioxide and, especially in Indonesia, posed a direct threat to the survival of species such as the orang-utan and Sumatra's tiger, rhino and elephant.

United Biscuits said it has been working with WWF and New Britain Palm Oil which will supply palm oil that has been segregated throughout the supply chain to ensure that all of it has come from sustainable plantations.