Around 180 Sufi Muslims have been arrested in Iran after attacking a Shia mosque where a cleric labelled their religion "illegitimate", say reports.
The Sufi lodge was partially destroyed in the clashes
The confrontation in the western city of Boroujerd led to a shootout between the Sufis and police that reportedly left about 80 people injured.
Sufis are tolerated in the Islamic Republic though some religious leaders have branded them "a danger to Islam".
About 1,000 Sufis were held last year in clashes at Iran's holy city of Qom.
The disorder in Boroujerd, about 320 km (200 miles) south-west of the capital, Tehran, broke out on Saturday morning, according to local news agencies.
Sufis attacked a Shia mosque after a cleric said their lodge should be shut down.
On Sunday, police reportedly raided the Sufi lodge to make arrests and bloody clashes ensued, resulting in the building being partially destroyed.
Sufism is Islamic mysticism. Sufis believe in a mystical path to God through prayer, dance and music.
There are Sunni and Shia Sufis. Their practices are often seen as unorthodox and illegitimate by more conservative Muslims.