Khaled Hamza, editor of the Muslim Brotherhood Web site, confirmed to FOXNews.com that 10 members of the Brotherhood's parliamentary bloc received official invitations to attend the speech.
The list includes Mohammed Saad el-Katatni, head of the parliamentary bloc.
The expected attendance of the Brotherhood members already is stirring some criticism from conservatives in the U.S. who say they do not represent the kind of moderate Muslims Obama should be appealing to.
"What kind of signal are we sending?" said Rep. Pete Hoekstra, ranking Republican on the House intelligence committee, warning that such an invitation will be seen more as a sign of weakness than strength. "I think the president takes some big risks by unilaterally putting out these olive branches."
The Muslim Brotherhood, though, has a complicated history.
Though the hard-line group, which calls for an Islamic state and has close ties to the militant Hamas, is officially banned in Egypt, its members have considerable sway in the country and its lawmakers, who run as independents, hold 88 seats in Egypt's 454-seat parliament.
The Brotherhood renounced the use of violence in the 1970s and now says it seeks democratic reform in Egypt. It is the most powerful opposition movement in the country, and many analysts argue Washington should engage the Brotherhood directly to show it is open to dealing with nonviolent Islamist movements.
The group is not on the State Department's official list of foreign terrorist groups.
Despite some reports suggesting the Obama administration arranged the invitations, officials said invitations were only sent out by Cairo University and Al-Azhar University.
"I can tell you that invitations have gone out to the full range of actors in Egyptian political society," Obama adviser Denis McDonough said Friday.
It is unclear what Muslim Brotherhood members hope to hear in the speech. One member said last month on the group's Web site that Obama's trip to Egypt would be "useless" unless preceded by concrete changes in U.S. foreign policy.
Scott Wheeler, director of the National Republican Trust PAC, slammed the administration for apparently allowing the Muslim Brotherhood into the event.
In a written statement, he charged that the group is linked to "international terrorists attacks, advocates suicide bombings, and the very founders of Hamas."
"The American people did not vote for President Barack Hussein Obama to make peace with Muslim terrorists," he said in the statement.
Obama is hoping to strengthen fractured ties between the East and West in his Cairo speech Thursday.
The Associated Press contributed to this report.