Newcastle City Council believes that up to 200 cases of sickness have been reported following the city's Street Spice festival held last week.
Four people so far have proved positive for salmonella during initial tests carried out by environmental health officers.
Further results are expected to be available in due course.
12,000 people are believed to have visited the Street Spice festival while it was in Newcastle.
“The event organisers are cooperating fully and we are continuing to investigate the source of the outbreak.
"Please can anyone with symptoms contact Regulatory Services and Public Protection at the City Council on 0191 278 7878"
More top news
Hundreds of people have been sharing their views at a public meeting following the closure of a GP practice in rural Northumberland.
On the first day of the meteorological Autumn - what will the weather have in store?
Fans are being warned that counterfeit Rugby World Cup tickets are in circulation. Here is some advice on how to avoid being conned.