CAIRO – Egypt’s Muslim Brotherhood, the Islamist group set to dominate the new parliament, accused the country’s military rulers Thursday of trying to undercut the authority of elected legislators even before the house is seated.

The Brotherhood said it is boycotting a council appointed by the ruling generals to oversee the drafting of the new constitution and stayed away from a meeting to set up the panel Thursday.

In theory, the new parliament will be entrusted with forming a 100-member assembly to write the constitution. But the ruling military council says election results showed the parliament will not be representative, so they are appointing a council to ensure the process of drafting a constitution is protected from extremist religious ideas.

Muslim Brotherhood spokesman Mahmoud Ghozlan said his group will not be part of the new constitutional oversight council because it will deprive the parliament of its authority.

“The military council is determined to turn against the will of the people,” he said. “To those who voice fear of Islamists, this is just blackmailing.”

Islamist groups won about 68 percent of seats in the first round of parliamentary elections, according to Associated Press calculations based on official results. The Muslim Brotherhood dominated the vote, with about 47 percent, while the second-place Al-Nour — an even more conservative Islamist party — won about 21 percent. Only four women won among 150 of 498 seats determined.

The elections were the first since Hosni Mubarak’s February ouster in a popular uprising, and are considered the freest and fairest vote in Egypt’s modern history. There are still two more rounds over the coming month, but they are not expected to alter the outcome.

A collision between the powerful Brotherhood and the military was much anticipated. A secular institution that has traditionally controlled access of Islamists to its ranks, the military said it is the only authority that will have the right to form a new government and spoke about determination to oversee the writing of the constitution. Recently, the ruling generals have indicated the new parliament will be weakened.

The 83-year-old Brotherhood was banned under Mubarak and subjected to waves of arrests and oppression but still managed to build the country’s strongest political organization, fielding independent candidates in previous elections. With Mubarak’s fall, it was the group’s chance to exert its power openly.