Mr Parish, who is chair of the Environment, Food and Rural Affairs Select Committee in parliament, complained to the British Retail Consortium in a letter about the amount of imported product in shops.
The letter read: “As the British lamb season is just starting, we do expect to see our supermarkets supporting British farmers and providing consumers with the choice of British meat.
“The current reliance on imported lamb by major supermarket retailers is a real concern to me, especially at this critical time when the UK is preparing to leave the European Union.”
Mr Parish also called on the retailers to do more to support and promote British lamb and said British lamb products should not be undercut by cheaper imported products or promotions.
He has previously raised the issue during Defra parliamentary questions.
NFU livestock board chairman Charles Sercombe said: “It is really good we have support from MPs.
“There is a need to make this point about how retailers are supporting British lamb and it is a message the NFU is very keen to deliver. Support from any quarters is very gratefully received.”