NY Times today:
Iran has told the International Atomic Energy Agency that it will refuse to answer questions about a second, secret uranium-enrichment program, according to European and American diplomats. The existence of the program was disclosed by President Mahmoud Ahmadinejad earlier this month.
The diplomats said Iran had also refused to answer questions about other elements of its nuclear program that international inspectors had focused on because they could indicate a program to produce nuclear weapons. The diplomats insisted on not being identified because of the delicacy of continuing negotiations between Iran and the West.
A two-pipe problem, Watson