BAGHDAD — Rekindling sectarian rivalries at a sensitive time, Iraq's parliament on Saturday voted to fully legalize state-sanctioned Shiite militias long accused of abuses against minority Sunnis, adopting a legislation that promoted them to a government force empowered to “deter” security and terror threats facing the country, such as the Islamic State group.

The legislation, supported by 208 of the chamber's 327 members, was quickly rejected by Sunni Arab politicians and lawmakers as proof of the “dictatorship” of the country's Shiite majority and evidence of its failure to honor promises of inclusion.

“The majority does not have the right to determine the fate of everyone else,” Osama al-Nujaifi, one of Iraq's three vice presidents and a senior Sunni politician, said after the vote, which was boycotted by many Sunni lawmakers.

“There should be genuine political inclusion. This law must be revised.”

Another Sunni politician, legislator Ahmed al-Masary, said the law cast doubt on the participation in the political process by all of Iraq's religious and ethnic factions.

“The legislation aborts nation building,” he said, adding it would pave the way for a dangerous parallel to the military and police.

A spokesman for one of the larger Shiite militias welcomed the legislation as a well-deserved victory. “Those who reject it are engaging in political bargaining,” said Jaafar al-Husseini of the Hezbollah Brigades.

“It is not the Sunnis who reject the law, it is the Sunni politicians following foreign agendas,” said Shiite lawmaker Mohammed Saadoun.

The law, tabled by parliament's largest Shiite bloc, applies to the Shiite militias fighting the Islamic State group as well as the much smaller and weaker anti-Islamic State Sunni Arab groups. Militias set up by tiny minorities, like Christians and Turkmen, to fight the Islamic State group are also covered.

According to a text released by parliament, the militias are now an “independent” force that is part of the armed forces and report to the prime minister, who is also the commander in chief.

The new force would be subject to military regulations, except for age and education requirements — provisions designed to prevent the exclusion of the elderly and uneducated Iraqis who joined the militias. The militiamen would benefit from salaries and pensions identical to those of the military and police, but are required to sever all links to political parties and refrain from political activism.

The legislation came at a crucial stage in Iraq's two-year-long fight against the Islamic State group, a conflict underscored by heavy sectarian tensions given that the group follows an extremist interpretation of Sunni Islam and the security forces are predominantly Shiite. The Shiite-led government last month launched a massive campaign to dislodge the Islamic State group from predominantly Sunni Mosul, Iraq's second-largest city and the last major urban center still held by the extremist group.

Through the military, the government has used the campaign to project an image of even-handedness, reaching out to the city's residents and promising them a life free of the atrocities and excesses committed by the Islamic State group. It has also excluded the Shiite militias from the battle, winning a measure of goodwill from the Sunnis. But Saturday's legislation may stoke the simmering doubts of many Sunnis about the intentions of the government.