Scottish & Newcastle UK risks a run-in with unions after contracting out its distribution services for pubs.
S&NUK says the deal with logistics firm Keuhne & Nagel will allow the brewer to concentrate on developing brands.
But the Transport & General Workers Union called the deal a "slap in the face" and puts the jobs of several hundred of S&NUK's logistics staff at risk. However, S&NUK said the only job losses would be in management.
Under the deal, Keuhne & Nagel will take over all S&N's distribution of drinks to pubs under a new division, KN Drinks Logistics.
Keuhne & Nagel has handled some distribution work for S&NUK since 1991 but from 3 July it will also take charge of deliveries from warehouses and regional depots to licensed premises. S&NUK promised "business as usual" for pubs with no immediate changes to its distribution network.
The deal will net S&NUK £30m and the company said it will free up further cash to invest in its brands in the future.
Company managing director John Dunsmore said: "The big prize is in terms of the culture of the organisation. We are focusing on brands and sales where we think we can make the most difference."
Dunsmore said the new, larger company would help win business in the off-trade, which is necessary while the on-trade beer market is falling 3% each year.
Dunsmore reckoned regional brewers might be more inclined to sign up to KN Drinks Logistics because it will not include the S&NUK name.
S&NUK said all logistic staff currently employed by Kuehne & Nagel and S&NUK will transfer to KN Drinks Logistics, which will employ 2,900 people.
T&G's national organiser Brian Revell said: "The company has signed the contracts without meeting its fundamental obligation to allow us to explore alternative solutions through meaningful consultations. Our drivers, draymen and warehouse workers at Scottish and Newcastle whose jobs are now threatened with outsourcing are bitterly disappointed.."
However, S&NUK said it exceeded the legal requirements on consulting with employees.
On job losses, Dunsmore said: "There will be some duplication at management and administration level but no job losses at draymen and warehouse level. We believe this is a really good venture for the employees because we think it's going to be a successful business."
T&G bosses are to meet S&NUK this week.