British cows entering Northern Ireland for meat production or breeding have to have their UK ear tags replaced with an EU Northern Ireland code because the livestock comes from a non-EU or ‘third’ country. EU cows transiting through Britain to Northern Ireland do not need to be retagged.

British cows arriving in Northern Ireland normally had three ear tags, two dating from birth. The EU rules mean another two NI tags must be attached.

“EU traceability rules require that animals are identified with a tag complying with EU rules, but it does not require UK tags or other tags to be removed,” the spokesman said.

Brussels believes the rules are needed to differentiate between cows in Northern Ireland, which are subject to EU rules, and those in the rest of the UK.

British negotiators have argued the UK system already makes it possible to tell the difference.

The rules require veterinary inspectors to supervise the retagging and new tags to be bought by Northern Irish farmers. Old and new numbers must be recorded by Northern Ireland’s Department of Agriculture, Environment and Rural Affairs.

The UK wants to cut the number of Irish Sea border checks on British goods because it is having a chilling effect on trade with Northern Ireland. Talks continued this week.

Last June, the commission changed EU rules to allow cows moving to and from Britain and Northern Ireland multiple times to do so without being tagged each time.