The confectionery giant Cadbury is to be prosecuted over a salmonella scare that saw more than 1m chocolate bars recalled from shops last year, it was confirmed today.

Birmingham city council said the Birmingham-based firm was accused of placing "unsafe" products on the market.

The prosecution - which the Guardian earlier this year reported was likely - follows an extensive investigation by the council's public health officers, who have been interviewing staff and gathering evidence.

Cadbury will be prosecuted over its alleged failure to "immediately inform" the authorities about the contamination, which made dozens of people ill and sparked a nationwide health alert.

There will also be a third charge of failing to "identify hazards" from chocolate bars contaminated with salmonella and failing to pinpoint "corrective actions".

Each of the three offences carries a maximum penalty of unlimited fines and/or two years in prison, council officials said.

Cadbury will appear before Birmingham magistrates court on June 15.

"We have fully cooperated with the authorities throughout their inquiries and we will examine the charges that have been brought," a company statement said. "As there is now legal action pending, it would be inappropriate for us to comment further."

The health scare originated at the company's factory in Marlbrook, Herefordshire, and was blamed on a leaking pipe carrying waste water from cleaning machinery.

Although the problem was discovered in January and confirmed in February, Cadbury allegedly failed to inform the authorities until June.

Government health officials said up to 37 of 56 cases of salmonella montevideo reported between March and July last year were identical to bacteria found in the company's confectionery.

The scare damaged consumer confidence in one of Britain's best-known brands, and Cadbury said it had cost it around £30m.

The chocolate bars recalled from retailers included 1kg Dairy Milk bars, Dairy Milk Buttons Easter eggs and other Dairy Milk lines including the 250g Dairy Milk Turkish and Freddo bars.