The NFU is supporting a group of members who have filed a legal challenge against the Animal and Plant Health Agency (APHA) in a case about compensation for poultry farmers affected by bird flu.
The union said it had decided to join the case as an interested party in support of the members and the wider poultry sector.
The members bringing this case argue that APHA had misinterpreted the legislation on compensation paid to poultry farmers affected by avian influenza.
This was leading to substantial shortfalls in the payments being made, the NFU said.
The union's poultry board chair, James Mottershead said the financial implications of the avian influenza outbreak were 'huge'.
He said the case could have far-reaching implications for other NFU poultry members.
"The emotional strain on affected farmers, their families and staff members is devastating, with many now forced to re-consider their future," he added.
"This is the worst outbreak of the disease in the UK to date, with no end in sight. We need this matter resolved as soon as possible."
The NFU and its Legal Assistance Scheme have also committed to providing significant funding to support the members bringing the claim.
