Greggs has revealed further shake-ups in its manufacturing structure following news it is to convert its bakery in Birmingham into a distribution centre.

Hundreds of jobs are said to be at risk after the business announced it is changing operations at its bakeries at Treforest, Wales and in Cambuslang, near Glasgow.

Production of confectionery items including doughnuts are to be transferred from the Treforest site to other regional bakeries over the next two years, with Treforest to focus on sandwich bread production. Workers have been told 90 to 120 jobs are to go over the next 12 months to two years.

"We have entered a period of consultation regarding these proposals with our team in Treforest," said a spokesperson for Greggs.

Union Usdaw said restructuring at the Clydesmill Bakery, Cambuslang, has put a further 100 jobs at risk as Greggs concentrates production on “centres of excellence”.

“Greggs bakery staff are now very concerned about the future after this announcement,” said Usdaw national officer Dave Gill, adding the union is entering consultation talks with the company

“We will interrogate the business case for their proposals,” he said. “Our priorities are to save as many jobs as possible, maximise employment in the business and seek the best possible deal for our members.”

Greggs told British Baker is has proposed that Clydesmill becomes a "Combined Distribution and Production Centre of Excellence with increased shop distribution capacity for Scotland and production focused on certain products".

News of the Scottish and Welsh plans follows Greggs announcing it will turn its Birmingham bakery into a ‘logistics centre of excellence’.

Greggs described the move as the next phase of a five-year, £100m investment in its supply chain that was announced in March last year. The business closed its bakery in Twickenham in November and opened a new distribution centre in Enfield, which it said was operating well.

Greggs last week announced a 7% increase in group sales in the year to 31 December 2016, which included its 13th consecutive quarter of like-for-like growth.

In a trading statement, Greggs said it plans to continue to invest in developing its supply chain in the coming year.