Thousands of Sunnis rallied Friday in western and central Iraq, denouncing the Shiite-led government's policies they claim sideline their sect and saying that recent concessions by the authorities are not enough.

The protests — the fourth Friday in a row of rallies in Sunni parts of the country — come as tensions are rising among Iraq's ethnic and sectarian groups, threatening to plunge the country into more instability.

In the beginning, the protests were concentrated in Iraq's western Anbar province but on Friday, they spread to the central city of Samarra and other Sunni strongholds.

The protests first erupted after last month's arrests of bodyguards assigned to Finance Minister Rafia al-Issawi, one of the central government's most senior Sunni officials. He has since become a rallying point for the demonstrators, who are angry over perceived second-class treatment by the government.

In Samarra, about 3,000 took to the streets Friday, demanding that the government release more Sunni detainees from jails and halt allegedly random arrests of Sunnis in their province.

Sheik Hassan al-Samarie, one of the organizers of the Samarra rally, said the Sunnis there are disappointed by the slow response of Prime Minister Nouri al-Maliki's government in fulfilling their demands.

"We are fed up with the void promises of the government," al-Samarie told The Associated Press over the phone. "Our demands must be achieved very soon, otherwise the number of the protesters will increase."

The demonstrators held banners reading, "We are nobody's slaves" and "The government should stop the random arrests immediately." The crowd also chanted: "Al-Maliki, leave!"

Haitham al-Hadad, one of the protesters, urged the government to stop discrimination against Sunnis.

"Iraqi laws should be implemented on everybody, not only Sunnis," he said.

Sectarian tensions are a major driver of the violence that continues to plague Iraq. The 2006 bombing of the gold-domed al-Askari shrine in Samarra, which was blamed on al-Qaida, sparked years of retaliatory bloodshed between Sunni and Shiite extremists. The violence left thousands of Iraqis dead and pushed the country to the brink of civil war.

Violence has since dropped overall in Iraq, but attacks still happen frequently, usually in the form of Sunni militants targeting Shiites or security forces in an attempt to undermine the government's authority.

Thousands of Sunnis also rallied in Friday in Anbar and Ninevah provinces, saying recent concessions by the Shiite-led government fall short of their demands.

The government over the past few days freed hundreds of inmates in a gesture to the Sunni protesters, and promised more would be released. It gave no details on the backgrounds or alleged crimes of those freed. The release of detainees has been one of the main demands of the rallies but apparently, the move did little to calm the tensions.