NBC is pulling the plug on its high-profile, eight-part “9/11” miniseries, a project that top network executives were heavily promoting as late as the May upfronts. The project was designed to give a far-reaching account of the airline hijackings and terrorist attacks on the World Trade Center and the Pentagon on Sept. 11, 2001.

Sources said the NBC Universal Television Studio/Imagine Television/Twentieth Television project, which was being written by Graham Yost (“From Earth to the Moon,” “Boomtown”) and executive produced by Imagine’s Brian Grazer, Ron Howard and David Nevins, was no longer being developed. No cast or airdates had been announced, but “9/11” was expected to air in the 2005-06 season.

In March NBC consultants were added to the production team, including authors Peter Lance (“1,000 Years for Revenge: International Terrorism and the FBI — the Untold Story”) and Steve Coll (“Ghost Wars: The Secret History of the CIA, Afghanistan, and Bin Laden, from the Soviet Invasion to September 10, 2001”) and TV writer Fred Golan (“Law & Order: Trial by Jury”). In addition, The New York Times was added as a consultant by allowing access to its “Portraits of Grief” series, which profiled every victim of the attacks that the newspaper could identify.

NBC declined to comment on the project.