Dina Habib Powell, a senior aide to U.S. Secretary of State Condoleezza Rice, resigned Wednesday to join a Wall Street investment bank, State Department deputy spokesman Tom Casey said.

Powell, 33, was assistant secretary of state for educational and cultural affairs and deputy to Underscretary of State Karen P. Hughes before her resignation.

Powell said she resigned for personal reason.

She is one of the youngest senior State Department diplomats, and a key architect of a Rice initiative to improve the United States' image abroad.

Powell, who emigrated from Egypt to Texas with her parents, is the highest-ranking Arab American in the Bush administration.

Days before Powell's resignation, Barry Lowenkron, assistant secretary of state for democracy, human rights and labor, resigned to join a private charitable foundation. In addition, one of Rice's two deputies, foreign aid director Randall Tobias also quit due to involvement of sex scandal. ?