Italy is facing pressure from the European Commission to provide information over the possible contamination of buffalo mozzarella.
If Italy fails to provide the requested information by 1800 (1700 GMT) on Thursday, the commission says it will consider "safeguarding measures".
Japan and South Korea have already imposed an import ban on the cheese.
High levels of carcinogenic dioxins were reportedly found in buffalo herds whose milk is used to make the cheese.
The Italian authorities sent some information on Wednesday, but it was found to be incomplete, European Commission health spokeswoman Nina Papadoulaki said on Thursday.
"Apparently they [the affected cheese stocks] are just in the local market, in the Italian market," she told a news conference later on Thursday.
"We are talking about four holdings that are positive and 23 dairy establishments. The quantities of dioxins were higher than the EU legislation requires, but it was not excessive."
The commission is calling for "the immediate withdrawal from the market of all contaminated products, the name of the buffalo farms placed under bans, the list of contaminated products, information on the control measures put in place and guarantees on prevention measures".
On Wednesday, Italy sealed off more than 80 dairy farms after finding higher-than-permitted levels of dioxins, the health ministry said.
Special checks were being made to guarantee the safety of the cheese, the ministry said.
Foreign Minister Massimo D'Alema said international alarm was "totally exaggerated and unjustified".
Spot checks
Last week, veterinary tests were ordered on more than 60 buffalo herds in the Naples area after spot checks showed milk contamination from toxic waste illegally dumped by criminals on agricultural land used for pasture.
Although cheese producers says only a tiny proportion of their production could be affected, buffalo farmers are now panicking after an unprecedented fall in milk sales of up to 60%, says the BBC's David Willey in Rome.
Police are investigating whether feed given to herds around the city of Naples was tainted.
Mozzarella production is big business in Italy, with herds of a quarter of a million buffalo producing a total of 33,000 tonnes of mozzarella cheese each year, 16% of which is exported.
The Naples area has a chronic waste-management problem, made worse by the dumping of illegal industrial waste, much of it toxic, transported from Italy's industrial north.
Only in recent months have the authorities attempted to get to grips with the problem, which has become an issue in Italy's forthcoming general election, our correspondent says.
If Italy fails to provide the requested information by 1800 (1700 GMT) on Thursday, the commission says it will consider "safeguarding measures".
Japan and South Korea have already imposed an import ban on the cheese.
High levels of carcinogenic dioxins were reportedly found in buffalo herds whose milk is used to make the cheese.
The Italian authorities sent some information on Wednesday, but it was found to be incomplete, European Commission health spokeswoman Nina Papadoulaki said on Thursday.
"Apparently they [the affected cheese stocks] are just in the local market, in the Italian market," she told a news conference later on Thursday.
"We are talking about four holdings that are positive and 23 dairy establishments. The quantities of dioxins were higher than the EU legislation requires, but it was not excessive."
The commission is calling for "the immediate withdrawal from the market of all contaminated products, the name of the buffalo farms placed under bans, the list of contaminated products, information on the control measures put in place and guarantees on prevention measures".
On Wednesday, Italy sealed off more than 80 dairy farms after finding higher-than-permitted levels of dioxins, the health ministry said.
Special checks were being made to guarantee the safety of the cheese, the ministry said.
Foreign Minister Massimo D'Alema said international alarm was "totally exaggerated and unjustified".
Spot checks
Last week, veterinary tests were ordered on more than 60 buffalo herds in the Naples area after spot checks showed milk contamination from toxic waste illegally dumped by criminals on agricultural land used for pasture.
Although cheese producers says only a tiny proportion of their production could be affected, buffalo farmers are now panicking after an unprecedented fall in milk sales of up to 60%, says the BBC's David Willey in Rome.
Police are investigating whether feed given to herds around the city of Naples was tainted.
Mozzarella production is big business in Italy, with herds of a quarter of a million buffalo producing a total of 33,000 tonnes of mozzarella cheese each year, 16% of which is exported.
The Naples area has a chronic waste-management problem, made worse by the dumping of illegal industrial waste, much of it toxic, transported from Italy's industrial north.
Only in recent months have the authorities attempted to get to grips with the problem, which has become an issue in Italy's forthcoming general election, our correspondent says.
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