Defying international calls to reach out to other sects, Iraq’s Shia rulers on Tuesday declared a boycott of the country’s biggest Sunni political bloc and accused Saudi Arabia of promoting “genocide.”

The United States, which occupied Iraq between 2003 and 2011, has conditioned military support for the government on the inclusion of Iraq’s Sunni minority.

Prime Minister Nouri al-Maliki, a Shia Muslim, appeared to move in the opposite direction, announcing a crackdown of police officers and politicians he considers “traitors” and lashing out at Saudi Arabia which has backed Sunni militant groups in Iraq in the past.

Sunni fighters from the Islamic State of Iraq and the Levant (ISIS) — a jihadist group that claims affiliation with Al Qaeda but is not recognized by the international terrorist organization — shocked the government in Baghdad last week when it conquered Iraq’s second biggest city, Mosul. They have since battled government forces north of the capital.

While Saudi Arabia has denied supporting ISIS, Iraq’s government said in a statement it held the kingdom “responsible for supporting these groups financially and morally and for the outcome of that — which includes crimes that may qualify as genocide: the spilling of Iraqi blood, the destruction of Iraqi state institutions and historic and religious sites.”

ISIS militants, who are also active in neighboring Syria in opposition to the Shia regime of President Bashar al-Assad, have boasted of massacring hundreds of Iraqi troops.

Maliki made similarly hostile remarks in March when he accused the Sunni monarchies in the Persian Gulf of “inciting and encouraging the terrorist movements” in his country. “I accuse them of leading an open war against the Iraqi government,” he said at the time.

Saudi Arabia and most of the other Gulf Cooperation Council states see Maliki as an ally of their nemesis Iran’s.

While condemning the violence, at least one of Iraq’s Sunni tribal federations supports the latest uprising, reflecting Sunnis’ discontent with the exclusionary policies of Maliki’s government. It has sidelined virtually all Sunni political parties.

Hassan Suneid, a close ally of Maliki’s, suggested on Tuesday the governing National Alliance should several its remaining ties with Iraq’s largest Sunni political bloc, Muttahidoon. “It is not possible for any bloc inside the National Alliance to work with Muttahidoon bloc due to its latest sectarian attitude,” he said in a television interview.

Sunni parties won slightly more seats in the Iraqi parliament in the 2010 election than Maliki’s State of Law Coalition but the prime minister subsequently reached out to his Shia rivals to form a new party, National Alliance, and remain in power. Sunnis were dismayed and turned out in few smaller numbers in the election earlier this year that saw Maliki reelected to a third term.