ISTANBUL, Jan 15 (Reuters) - Turkish police have detained 22 people behind a grassroots campaign to introduce Kurdish-language education in primary schools, the state-run Anatolian news agency said on Tuesday.

Responding to calls by the European Union, Turkey amended its constitution in October to allow for Kurdish-language broadcasts and publications, but continues to bar Kurdish in the classroom for fear it could erode state unity.

A state security court prosecutor launched a probe after a group, mainly women, submitted a signed petition to education officials in Istanbul calling for a repeal of the ban on Kurdish-language instruction.

Counter-terrorism police detained 34 people, but released 12, Anatolian said. The rest remained in custody on suspicion of having ties with the separatist Kurdistan Workers Party (PKK), which Turkey considers a terrorist organisation.

It was not immediately clear when the arrests occurred, and police officials were unavailable for comment.

The PKK has waged a 17-year armed campaign for a homeland in the mainly Kurdish southeast. More than 30,000 people have died in the fighting but violence dropped off sharply with the 1999 capture of PKK commander Abdullah Ocalan.

The EU, which Turkey aspires to join, has said the country must improve its chequered human rights record for membership talks to begin. The bloc has urged Ankara to expand civil liberties for the country's 12 million Kurds, who are not officially recognised as a minority group.