Guinness is racing to increase production after British pubs reported shortages of the popular stout following a surge in demand over the festive period.
Guinness reportedly raided its security stocks in Ireland in order to help fill the gap.
Parent company Diageo, which also owns brands such as Johnnie Walker and Gordon’s, described the sales growth as "extraordinary," with demand exceeding even the typical St Patrick’s Day peak.
It said a new factory in Kildare, Ireland would bring more capacity online.
Diageo chief executive Debra Crew confirmed that Guinness sales during October and November surpassed the usual St. Patrick’s Day figures, highlighting the drink’s booming popularity.
However, this surge in demand left many pubs struggling to keep up, facing shortages during the crucial Christmas period.
There were also reports that some pubs in London rationed the amount of Guinness that drinkers could buy to ensure customers had a fair share.
Ms Crew told reporters: “It has seen extraordinary growth in Britain, particularly at a time when the wider beer market is actually declining.
“Late last year, the demand was unprecedented. It was a sell-out period for the brand.
“We are working around the clock to replenish our stock levels and are boosting those quickly.
“We are spending €200 million (£166 million) on a new factory in Kildare, in order to bring more capacity online.”
A Guinness microbrewery is set to open in London’s Covent Garden in 2025.
The project will transform a section of the city into a vibrant microbrewery and cultural hub. The development will feature a range of amenities, including multiple bars, community spaces, event venues, a merchandise store, and a rooftop restaurant offering panoramic city views.
Guinness saw net sales grow by 13 per cent over the half-year to December.
It came as Diageo reiterated it is “not selling” Guinness, after reports that the group is considering a spin-off or sale deal of the historic Irish brand.
Analysts had suggested the group could get as much as £8 billion for the business if it sought a deal.
