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Egypt's military-backed interim leadership proclaimed Wednesday that a crackdown against two protest sites is inevitable, saying that nearly two weeks of foreign diplomatic efforts to peacefully resolve its standoff with the Muslim Brotherhood have failed.

The statements strongly suggested that Egypt's sharp polarization may spiral into even more bloodshed as thousands of supporters of ousted President Mohammed Morsi, a Brotherhood member, camp out at two main Cairo intersections and hold daily protests outside security buildings.

At stake is stability in the Arab world's most populous country. Already more than 250 people have been killed in violence since the military ousted Morsi more than a month ago, including at least 130 Brotherhood supporters in two major clashes between security forces and backers of the deposed president.

"The decision agreed on by all to clear the sit-ins is final and irreversible," Prime Minister Hazem el-Beblawi said on state television, reading a statement issued by the Egyptian Cabinet.

In response, top Muslim Brotherhood figure Mohammed el-Beltagy said the protesters are not concerned with talk of clearing the sit-ins.

"What we care about is for there to be clear talks about our position against the military coup and the importance of returning legitimacy," el-Beltagy told The Associated Press at the main protest site in the capital's Nasr City neighborhood. He said the Cabinet's statement makes "clear that they lack vision with regard to the political scene."

It was unclear what the crackdown would entail or when it would begin, but it appeared unlikely to start until next week. The Cabinet statement said the government was keen not to take action during Ramadan, which ends Wednesday. A separate statement by the interim president described the four official days of Eid celebrations that follow the Muslim holy month as "tolerant" and "harmonious."

The prime minister said the Cabinet "had hoped to solve this crisis during this period without the intervention of security forces," but that the sit-ins have not been peaceful and that the protesters have frightened citizens, blocked roads, attacked government buildings and threatened security.

"The use of weapons against the police or citizens will be dealt with with utmost firmness and strength," the prime minister added.

Still, it remained uncertain whether authorities would resort to a level of force that could leave scores more dead and invite world condemnation. In the past week, they have outlined plans to break up the sit-ins using more restrained measures, such as putting up cordons to block people who leave from returning. The statement from interim President Adly Mansour's office stressed that any actions would be legal.

Wednesday's announcements follow a flurry of diplomatic visits by envoys from the United States, the European Union and Arab Gulf states in an attempt to defuse the crisis and find a compromise to avert the use of force against the sit-ins.

"These efforts did not achieve the success that was hoped for, despite full support provided by the Egyptian government," Mansour said. "The state of Egypt appreciates the efforts of friendly nations and understands the reasons why they did not achieve their desired objectives, and holds the Muslim Brotherhood fully responsible for the failure of these efforts."

On a visit to Cairo on Tuesday, U.S. Senators John McCain and Lindsey Graham urged the government to release the Islamist leaders as a gesture to the Brotherhood or risk making "a huge mistake."

Mansour, who was installed as Egypt's interim president by the military after the July 3 coup, rejected the senators' message, calling it "unacceptable interference in internal politics." The coup followed days of mass protests by Egyptians calling for Morsi's ouster.

The McCain-Graham visit was carried out at U.S. President Barack Obama's request, but their message differed from his. For one thing, they called what happened on July 3 a coup, a word the administration avoided because it would trigger a suspension of the $1.3 billion a year in U.S. military aid to Egypt.

State Department spokeswoman Jen Psaki said "our position has not changed" regarding the word "coup." `'Sen. McCain and Sen. Graham are certainly entitled to their opinions, just as any member of Congress is."

The new Egyptian leadership, emboldened by mass demonstrations of support, has shown no sign of willingness to ease its crackdown on the Brotherhood. Court cases have been set to prosecute top Brotherhood figures for allegedly inciting violence. The government is also pushing ahead with the rewriting of the Islamist-drafted constitution as part of a plan that also calls for parliamentary and presidential elections next year.

The Brotherhood is demanding Morsi's reinstatement as Egypt's first freely elected president, though privately many of the pro-Morsi protesters say that the sit-ins are their last bargaining chip to press for the release of Morsi and other detained leaders and for guarantees that they will be included in politics.

Morsi faces accusations of conspiring with the militant Palestinian Hamas group to escape from prison in 2011. He has been held at secret locations since his ouster, though Egyptian authorities have allowed the EU's foreign policy chief Catherine Ashton and a group of African statesmen to visit him.

Emboldened Muslim militants have increased the frequency of their attacks against the Egyptian army on Sinai Peninsula to exploit the political turmoil since Morsi's ouster. On Wednesday, Egypt's military spokesman said 60 Islamic militants have been killed and 103 arrested on the peninsula as part of the army's operations there over the past month.

Also Wednesday, a security official said pre-dawn clashes between Morsi supporters and residents of Egypt's Mediterranean city of Alexandria left one person dead and dozens wounded. Residents of the Manshiya neighborhood were angered by marchers who were chanting against the country's armed forces. It was not immediately clear what sparked the violence.

The official, who spoke anonymously in line with regulations, said 46 people were wounded, including some by gunshot and birdshot, in the violence.