THE cost of a can of Guinness could rise if a new customs border or tariffs are introduced between the Republic and Northern Ireland when the UK leaves the European Union, it has emerged.

The black stout is one of Ireland’s most famous exports, but crosses the Irish border twice before being shipped from Dublin to Britain and beyond.

Guinness is made at the St James’s Gate brewery in Dublin, and then taken by tanker to east Belfast where it is canned and then sent back to Dublin Port for onward distribution.

Diageo, the Guinness owner, has estimated that a so-called “hard border” Northern Ireland and the Republic could cause delays of between 30 minutes and an hour, adding extra £85 for each lorry-load of Guinness.

Each year the company makes 13,000 beer-related border crossings in Ireland and Guinness contingency plans estimate the delays could amount to £1.1m in additional costs each year.

Diageo would either be forced to absorb that cost or pass it on to the consumer by raising the cost of a pint.

All Guinness consumed in Britain has been produced in Dublin since Diageo closed the Park Royal operation in north-west London 12 years ago.

Experts predict the drink is one of many products which will be affected should a hard border be introduced, with the list topped by meat and dairy items.

“We have suppliers here who have meat which leaves here at 6.30pm and is in south east England at 6.30am the next day,” said Seamus Leheny, head of policy for Northern Ireland for the FTA.

“Some of these suppliers are now having to consider whether they can continue with meat processing here or whether they move it to the UK.”

Kegs of draft Guinness being exported to the UK will also be impacted with customs expected to be reintroduced at Holyhead.

Like all big name exporters, however, they are expected to continue with “trusted trader” status which will rule out random customs checks.