Two more cases of Legionnaires' disease have been confirmed in Stoke-on-Trent, where one patient is in a critical condition.
Eleven people are being treated at the University Hospital of North Staffordshire, a number that has been rising since news of the outbreak was released on Tuesday.
Professor Harsh Duggal, of the Health Protection Agency's health protection unit in Stafford, said: "Our investigation into possible sources of the disease continues and we have been able to obtain detailed information on the movements of those affected."
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