The UK's biggest food manufacturer Premier Foods has announced a massive restructure, including the loss of almost 600 jobs and the closure of six factories by 2009.

Premier Foods has been reviewing its operations following the £1.2bn acquisition of RHM in March and the £460m acquisition of Campbell Soup Company in 2006.

As a result, the procurement team will be increased by 20, with RHM's former group procurement and logistics director Mark Hughes replacing Premier's head of procurement, Robert Lawson. Lawson will retain his directorship of mergers, acquisitions and investor relations.

But it has also led to the closure of all six of RHM's factories and the loss of 580 jobs. The newly integrated PLC will comprise three Premier plants at Histon, Bury and Knighton, and two ex-Campbell facilities at Worksop and Ashford and these will receive "significant investment" to incorporate the production from the six closures, said Premier Foods' chief executive Robert Schofield.

Production and 16 jobs from Wythenshawe, Manchester, which has 109 staff, will move to Premier Foods' Bury St Edmunds site in Suffolk as the manufacturing base for sauces and chutneys.

The Robertson's site in Droylesden, Manchester, which has been making jam since 1890, and at Ledbury, Hertfordshire, which produced preserves, will close with the loss of 253 and 177 jobs respectively. Production will transfer to the Histon plant, near Cambridge, creating 87 new jobs.

Mr Kipling cakes will be manufactured at Knighton as RHM's catering operations and Foodservice brands in Bristol and Reading will close with the loss of 178 jobs.

The Knighton plant in Staffordshire, which employs 305 staff, will become Premier's main dessert producer, adding 23 new employees.

Bisto and Saxa salt manufacturing will also be switched with the loss of the 193-strong workforce at Middlewich, Cheshire.