The move is a bid by the UK's animal welfare group, which is joining forces with celebrity chef Jamie Oliver to improve the welfare of pigs.

The first part of the year long campaign will see the Society call on UK retailers to sign up to a voluntary agreement to label all pork products according to production method definitions developed by the RSPCA in association with the British pig industry.

This will allow for greater clarity for shoppers, said the Society.

In addition celebrity chef Jamie Oliver has been working with the RSPCA on the plight of pigs, and is sure to cook up some debate when his new programme 'Jamie Saves our Bacon' is aired as part of Channel 4's 'Great British Food Fight' season later this month.

"It is hoped that Jamie's programme and the RSPCA campaign will help improve the lives of many millions of pigs who are reared for meat both here and in the EU. "The success of chicken campaigns run by RSPCA and chefs Oliver and Hugh Fearnley-Whittingstall in January 2008 have seen a jump in sales of higher welfare chicken and eggs - despite the difficult economic circumstances - and it is hoped the pig campaign will have a similarly positive impact," said a spokesman for the RSPCA.