The National Pig Association (NPA) said its GammonWatch campaign would see members conducting surveys at supermarkets across the country and reporting their findings in weekly bulletins.
Those retailers which choose to support British pork will be publicly commended.
NPA chairman Richard Lister said: “In addition to carrying out our own checks, we are asking shoppers to check gammon labels carefully this Christmas to ensure the product they buy is made from cured British leg of pork, and not from imported pork that has only been cured in Britain.
“If our prices fall any further we will see some pig farmers freezing all investment in new buildings next year and others quitting altogether, and either route will be a serious blow to an industry that is known the world over for its high-welfare, high-quality product.”
Typically, only 30 per cent of gammons for the festive market are British, despite there being a plentiful supply from domestic producers.
It comes as farmgate pig prices fell for the third consecutive month in October, leading to the share of retail prices received by producers declining to 34 per cent. This was the lowest share recorded since November 2004.
The NPA said it would continue to pressure retailers to sourcing more British pork, particularly at a time when so many producers were ‘in the red’.
NPA chief executive Dr Zoe Davies added: “We know from successive surveys that customers prefer to buy British pork and pork products even if it costs a penny or two more for the extra quality we offer.
“This is especially true since ‘Horsegate’ in 2013 when most retailers sought to reassure customers by promising to stock more British meat.”