Several Muslim families pulled their daughters out of schools in Russia's south after the girls were told they were not allowed to wear their hijabs, a top Muslim cleric said on Monday.
The Mufti of the southern Stavropol region Muhammad-Haji Rakhimov said he had received complaints from several parents whose daughters were for the first time not being allowed into their schools wearing the headscarves.
The situation resembles a "stalemate" because both the Muslim parents and school authorities refuse to budge, and several girls including second-graders have not been to school for two weeks now, he said.
"The parents of these girls are not letting them go to school, which can lead to the child welfare services taking them away," Mr Rakhimov said.
He could not explain the authorities' sudden change in school policies.
"There have not been any problems before this month."
He added that there were now "many girls" in the Stavropol region who were being kept out of school for this reason, and their parents were too poor to send them to private schools.
One such institution is a rural public school in the village of Kara-Tyube, close to the overwhelmingly Muslim region of Dagestan.
The school's list of rules posted on its website says that students' appearance should be in line with the "business style used in a secular society, excluding provocative elements".
Russia's pro-government newspaper Izvestiya quoted the school's director Marina Savchenko as saying that girls would not be permitted in class in their hijabs, but that they could wear ordinary headscarves instead.
It added that the parents had filed a complaint with the local prosecutor.
There are about 20 million Muslims in Russia, most of them living in the mountainous North Caucasus, as well as in Tatarstan and Bashkortostan on the Volga River.