Diageo has announced that it intends to pull out of its Waterford city facility ending hundreds of years of brewing on the site.

Guinness will close its plant by the end of the year with the loss of 16 full-time and six support staff.

The plant makes Guinness flavour essence (GFE), a liquid concentrate made from barley, which is used in all Guinness brewed worldwide.

Though parent company Diageo said the plant was under review, the closure of the operation still came as a shock to the workers involved.

Diageo invested €40 million in the brewery in 2004 and it remains a state-of-the-art facility.

The company is now looking to consolidate its brewing operations in an expanded facility in St. James’ Gate.

Siptu representative Terry Bryan said the workers were particularly shocked that the plant is closing at the end of this year.

When Diageo announced that it was closing its Dundalk and Kilkenny facilities, the lead in time was almost five years.

He said that the workers did not intend to take the proposed closure as a “fait accompli” and would be making the case for it to remain open.

In the event that it does remain open, he said the workers would look for deployment to the new facility in Dublin and decent redundancy terms.

Diageo Europe beer supply chain director Paul Armstrong said the decision was being made with "sadness and regret" but the company was already working with Enterprise Ireland to find an alternative use for the site.

Sinn Féin Senator David Cullinane described the proposed closure as a "devastating shock to the workers and their families".

He said it was a further body blow for a city where unemployment is 25 per cent higher than the national rate.