An investigation into a national salmonella outbreak has been launched, health officials have said.
Public Health England (PHE) said it was looking into an outbreak of Salmonella Enteritidis which has affected 156 people.
Salmonella is one of a number of bacteria that can cause food poisoning.
Officials are looking into cases across Hampshire, London, the West Midlands and Cheshire and Merseyside, a PHE spokeswoman said.
The cases occurred in "isolated clusters" over several months but officials now say they could be potentially linked.
Genetic tests suggest that the cause of illness in the 156 people could have come from a single source, PHE said. PHE investigators are working alongside the Food Standards Agency to look into the cause of the outbreak - which may have also affected people in France and Austria.
Dr Paul Cleary, a consultant epidemiologist leading the PHE investigation, said: "We are working with our colleagues across PHE, at the Food Standards Agency, in local authorities and with other public health organisations in Europe to investigate the cause of this outbreak.
"We are making good progress and hope to have more conclusive evidence shortly.
"We will continue to monitor the situation and if there is any further public health action necessary then we will ensure that this takes place."
Across England experts are examining 55 cases in Hampshire, 32 of which have been connected with an oriental restaurant, and 33 cases in Cheshire and Merseyside, 31 of which have been linked to one oriental takeaway.
PHE are also looking at 43 cases in the West Midlands, 34 of which were connected with the Birmingham Heartlands Hospital outbreak.
They are also looking at 25 cases in London. Salmonella Enteritidis is a strain of bacteria that causes gastrointestinal illness and is often linked to poultry or eggs.