(RNS) -- President Bush has apologized to American Muslim organizations for an incident last week in which a Secret Service agent asked a member of their delegation to leave a White House meeting, but some delegation members say they want Bush to investigate an "alarming trend" of discrimination against American Muslims. "Although we appreciate and accept the President's apology, we are nonetheless very concerned by this latest incident, which is part of an alarming trend seemingly targeting American Muslims," read a statement from the American Muslim Council, one of the organizations that attended the White House meeting. "African-Americans, who represent a significant segment of the American Muslim community, have been targeted for decades. We feel the president needs to initiate an investigation into these types of incidents in order to determine their sources." The council pointed out that they had "supported Bush for his vision of a gentler, compassionate America where all its citizens are treated with respect and dignity." "We need strong action to confirm that promise," the statement said. Last Thursday (June 28), about 25 representatives of American Muslim organizations walked out of a meeting with the Rev. Mark Scott -- associate director of the White House Office of Faith-based and Community Initiatives -- after the Secret Service asked college student Abdullah Al-Arian to leave. Al-Arian is an intern in the office of Rep. David Bonior, D-Mich. No reason was given for the request, Faisal Gill, of the American Muslim Council, told Religion News Service. But some suspect the incident was linked to the political activism of Al-Arian's father. Sami Al-Arian is president of the National Coalition to Protect Political Freedoms, which has battled the U.S. government's use of "secret evidence" (evidence never disclosed to the defense team) in deportation proceedings regarding suspected terrorists. The college student is also the nephew of Mazen Al-Najjar, a Palestinian professor whom the government recently freed after holding him in custody for about three years on the basis of secret evidence. The government had claimed to possess evidence that connected the man to a terrorist group. President Bush "is very upset" about Thursday's incident, White House Press Secretary Ari Fleischer announced Friday (June 29). "The president is very concerned that an action was taken that was wrong and inappropriate, and the president apologizes for it on behalf of the White House," Fleischer said. "In this one instance, the Secret Service made a mistake. They've acknowledged it; they have said so. They will continue to say so, and the president is concerned about it to the point where he does apologize."