Secretary of State Hillary Rodham Clinton on Wednesday suggested there was a link between the Qaeda franchise in North Africa and the attack at the American diplomatic mission in Benghazi, Libya, that killed the American ambassador and three others. She was the highest-ranking Obama administration official to publicly make the connection, and her comments intensified what is becoming a fiercely partisan fight over whether the attack could have been prevented.

Mrs. Clinton did not offer any new evidence of a Qaeda link, and officials later said the question would be officially settled only after the F.B.I. completed a criminal inquiry, which could take months. But they said they had not ruled out the involvement of Al Qaeda in the Islamic Maghreb — an affiliate of the international terrorist group with origins in Algeria — in an attack the administration initially described as a spontaneous protest turned violent.

Her remarks added to the administration’s evolving and at times muddled explanation of what happened on the evening of Sept. 11 and into the next morning. Republicans in Congress have accused President Obama of playing down possible terrorist involvement in the midst of a re-election campaign in which killing Osama bin Laden and crippling Al Qaeda are cited as major achievements.

Mrs. Clinton made her remarks at a special United Nations meeting on the political and security crisis in the parts of North Africa known as the Maghreb and the Sahel, particularly in northern Mali, which has been overrun by Islamic extremists since a military coup helped lead to the division of that country this year.