WASHINGTON — A dozen Nobel Peace Prize laureates are urging President Obama to make “full disclosure to the American people of the extent and use of torture” by the United States, including the release of a long-delayed Senate report about the C.I.A.’s torture of terrorism suspects after the attacks of Sept. 11, 2001.

The laureates told Mr. Obama, who was awarded the Peace Prize himself in 2009, that the report’s prospective release has brought the United States to a “crossroads,” and that he must do more to bring closure to an era when the United States set an example that “will be used to justify the use of torture by regimes around the world.”

“It remains to be seen whether the United States will turn a blind eye to the effects of its actions on its own people and on the rest of the world, or if it will take the necessary steps to recover the standards on which the country was founded, and to once again adhere to the international conventions it helped to bring into being,” they wrote.

The joint letter was organized by two of the laureates, Archbishop Desmond Tutu of South Africa and former President José Ramos-Horta of East Timor, and is part of a broader online petition campaign at TheCommunity.com, whose chairman is Mr. Ramos-Horta. An advance copy was provided to The New York Times.