Scores of people in the Netherlands and the US have caught salmonella after eating Dutch smoked salmon, say Dutch health authorities.
About 200 people have fallen ill in the Netherlands along with about 100 people in the US, said the National Institute for Public Health (RIVM).
An RIVM official told the BBC that this could be the "tip of the iceberg".
Smoked salmon made by the Dutch fish producer Foppen is being taken off the shelves.
Foppen supplies major supermarket chains including large retailer Albert Heijn, said the Dutch food safety authority, the NVWA.
"Some 200 people have fallen ill through contaminated salmon" in the Netherlands, said the RIVM, while about 100 people in the US are infected "by the same type of salmonella".
But this was "probably the tip of the iceberg", the institute's Hareld Wychgel told the BBC - "the real number of infected people is likely to be much higher".
Smoked salmon produced by Foppen has been taken off the shelves in the Netherlands, and an international recall targeting salmon sold in the US was being prepared.
In a statement on its website, Foppen offered its "sincere apologies for any inconvenience".
Infection normally causes diarrhoea, abdominal cramps and sometimes fever and vomiting, says the UK's Health Protection Agency.
The symptoms usually clear up in four to seven days, but in some cases treatment may be required for dehydration.