CAIRO — Egypt's interim military rulers established a system Wednesday for what is promised to be the country's first free and open election, laying out a complicated plan evidently designed as a compromise between the competing demands of liberal and Islamist groups.

The parliamentary elections, which follow the popular revolution that ousted President Hosni Mubarak in February, are being watched closely around the region as a test of the Arab democracy movement. Activists here have anxiously awaited more details, both to ascertain the military's commitment to democracy and to allow candidates to begin to campaign. The new Parliament is expected to initiate the writing of a new constitution.

Rejecting the suggestions of U.S. officials and many human rights groups, the military said that for reasons of national sovereignty it would not invite international monitors to oversee the elections. But the military said that independent Egyptian human rights organizations and other groups would be free to do so. For the first time complaints about electoral fraud or abuses will be resolved before a member is sworn in, and the military said it was also repealing rules that previously protected members of Parliament from legal action to expel them.

Maj. Gen. Mamdouh Shaheen, speaking on behalf of the military's ruling council, said that "the electoral process" would begin in September in compliance with a referendum held in the spring. But for logistical reasons the final vote will take place in three stages over a month later in the fall.

Half of the seats will be chosen by voters in each district picking individual candidates running in winner-take-all races, as in the U.S. system. To fill the other seats, each voter will also chose a political party, and each party will receive a number of seats proportional to its share of the total vote, a system used in many countries to ensure the representation of minority views. Members of the upper and lower houses of Parliament will be elected simultaneously, with two lines leading to two ballot boxes at each polling place. Districts have not yet been drawn.

The defense minister, acting as interim president, will retain Mubarak's power to name 10 of the 514 members of the lower house. But Shaheen said the military would not exercise the president's previous prerogative to name a third of the members of the upper house.

The military said it was abandoning a quota for the number of women members of Parliament, an approach that Mubarak had imposed. It was widely seen at the time as a tactic to boost his governing party. But the military said it would retain an anachronistic requirement — widely ignored or abused under Mubarak — that half the seats go to workers or farmers. The military did not spell out the criteria for qualification but said a lawmaker who left his job category would be required to leave Parliament.

Samer Soliman, a political science professor and a founder of the newly formed Egyptian Social Democratic Party, called the system an improvement but criticized some elements, like the military's appointees and the absence of international monitors.

"The biggest issue is guaranteeing the integrity of the elections," he said.