Poland has for now banned the sale of all Czech alcohol except beer and wine.

Bootleg spirits such as rum or vodka have recently been found to contain methanol, which can cause illness in small quantities and blindness or death in larger doses.

Piotr Burda, head of Poland's toxicology center, said that alcoholics' doctoring up their drinks with industrial substitutes is common enough in Poland and that the illnesses, while highly coincidental, are not necessarily the result of poor Czech product.

"I have no evidence to suggest there is any link between the two," Burda said. "In Poland, the problem is above all alcohol substitutes consumed by alcoholics," he added.

Burda said that alcohol-related deaths have increased in Poland since a 2010 legal change to conform to EU rules forced the country to ease restrictions on methanol in cosmetics and chemicals such as perfume and radiator fluid. Since March, more than 80 such cases have been registered, or about 10 cases per month.

About 20 people have died in the Czech Republic and 40 remained in hospitals over the weekend from the outbreak, which claimed its first two victims on September 6, prompting Health Minister Leos Heger on Friday to ban the sale of liquor with an alcohol content higher than 20 percent. The prohibition applies to bars, supermarkets and restaurants.

In Slovakia, which borders both countries, eight people sought medical attention after consuming Czech liquor, with four hospitalized for alcohol poisoning. All are expected to survive. The group had bought 10 liters of the liquor over the Internet for a birthday party.

Czech media have reported that police have charged 23 people in connection with the spirits. The newspaper Lidove Noviny has reported that investigators suspect windshield cleaner was used.

mkg/kms (Reuters, AFP, dpa)