BAGHDAD — Tens of thousands of Sunni Muslims rallied on Friday in several Iraqi cities to protest what they describe as unfair treatment by the country’s Shi’ite-led government, extending concerns over rising sectarian tension in the country.

Sunnis have staged mass protests since late December. They are demanding that Shi’ite Prime Minister Nouri al-Maliki step down and are calling for the release of thousands of Sunnis they say were rounded up arbitrarily under the guise of counterterrorism regulations.