(CNN) -- Lacy underwear has effectively been "banned" by new regulations in Russia, Belarus and Kazakhstan, opponents say. But the issue is not one of modesty.
A customs union made up of the three post-Soviet countries introduced a regulation, which requires clothing in contact with skin to contain at least 6% of cotton, for safety reasons.
From July, underwear that does not meet this requirement will not be available in stores in the economic area. Production and import of these will also stop.
The regulations say this is designed to protect consumers against synthetic garments which don't absorb enough moisture. That could cause skin problems.
However, most luxury lingerie is made of materials with less than 4% cotton -- and will not be allowed.
Despite its supposed health benefit, the regulation has been badly received in Kazakhstan. Several Kazakh women were reportedly detained by the police in Almaty after protesting against the ban.
Scores of women have posted pictures of themselves in lacy underwear on social networks and compared the photos to images of Soviet-era style brown, shapeless underwear.
"Producers have known about the regulations for about 10 years," the customs union's regulation minister Valery Koreshkov said in a publicly released statement, adding the news should not be a surprise.
The union's regulation ТR СU 017/2011 was passed by the lawmakers in 2011, but will only come into effect this July. Other undergarments and linens are also affected.
But the reaction is putting union officials under pressure from textile producers and shoppers. In the same statement, Koreshkov said the union had already received several amendment proposals. Technical regulations are "not a dogma" and can change, the statement said. "These proposals should be considered by all the experts."
The customs union of the three counties was formed in 2010, and is moving towards a full European Union -style trade union. The Eurasian Customs Union is set to be formalized in 2015 and expected to expand to other countries in the region.