More than 80 placard-carrying pig farmers invaded Marks and Spencer's supermarket outside Lisburn at the end of last week to protest about the crisis in the industry. The farmers are demanding government help, and want leading stores to stock more locally-produced ham and pork. Marks and Spencer said that it already sourced large amounts of pigmeat from Northern Ireland producers. The local processing company, Unipork, said M&S's business was worth nearly £1 million last year, and is expected to be worth nearly £3 million this year.

But some producers have complained that the buying power of the major supermarkets means that they are being forced to reduce margins to unprofitable levels.

A massive backlog in the slaughter of pigs has been caused by last month's fire at the Lovell & Christmas processing plant in Ballymoney. Earlier in the week, farmers had released a number of pigs outside the official Hillsborough residence of the Secretary of State, Ms Mo Mowlam.

Economy minister Mr Adam Ingram said that the government was making every effort to ensure that the Lovell & Christmas plant was reopened as soon as possible.