Croatia's leading dairy, Dukat, has temporarily halted the purchase of milk from 180 local farms over high levels of a potentially carcinogenic toxin that has turned up in milk across the region.
It was the latest step in a Balkan milk scare triggered when laboratory tests confirmed higher-than-prescribed levels of aflatoxin, a product of the Aspergillus fungi often found in grains.
Dukat's general manager Alen Fontana said: "We are aware of the possible consequences for farmers and for us, but we had to suspend the purchase because of the safety of our consumers."
The dairy company said the high levels of aflatoxin were caused by the use of "improper cattle food".
It said that it would test milk from local farms again next week.
The scare follows a long drought in the region last year, which agriculture experts said had affected the quality of fodder.
Dukat and two other Croatian dairies, Vindija and Meggle, withdrew some of their long-life milk from shops earlier in February.
In neighbouring Serbia, authorities last Tuesday ordered an unspecified number of dairies to withdraw their milk pending the results of tests for aflatoxin conducted in the Netherlands.
The results are expected within days.
It followed a ban in Bosnia in late January on milk imports from some Croatian producers.
The ban was lifted this week, but the government said inspectors would continue testing imported and locally-produced milk.
Bosnia's state veterinary office said that milk from one Bosnian dairy had failed the tests.
Montenegro has also withdrawn from shops six brands of milk from neighbouring Bosnia and Serbia, and ordered all 16 local dairies and about 3,000 small producers to halt milk production pending further checks.
Montenegro has banned the import of fodder from Serbia, its main trade partner and supplier.
The scare comes as much of the rest of Europe is dealing with a scandal over the mislabelling of horse meat as beef in some processed foods, highlighting the complexities of the food chain across the trading bloc.