An Iranian flag flutters in front the International Atomic Energy Agency (IAEA) headquarters in Vienna, Austria, March 4, 2019. Photo: Reuters / Leonhard Foeger / File.

The United States on Tuesday said it was unacceptable that Iran was not fully cooperating with the International Atomic Energy Agency’s investigation of its nuclear program, but repeated it remained open to talks with Tehran on a “comprehensive deal.”

“Any indication that Iran is providing insufficient cooperation to the IAEA on a matter involving potential undeclared nuclear material or activities raises serious and profound questions,” the US statement to a quarterly IAEA Board of Governors meeting said.

“Iran‘s failure to resolve the Agency’s concerns on this matter is completely unacceptable and should be of deep concern to all who support the IAEA and its safeguards verification regime.”