"The United States wished for this representative body to fail, so that it could pursue its own unilateral initiatives and priorities through other more exclusive bodies and groups," Iranian ambassador Javad Zarif told a closing session of the conference on the nuclear Non-Proliferation Treaty (NPT).

Zarif placed the sole blame for the conference's failure to agree on measures to make the NPT more effective on the United States and accused Washington of sabotaging the event.

"It's no wonder the United States tried to create smokescreens at this conference to deflect attention from its abysmal record," said Zarif.

He also gave a harsh warning about the United States' current nuclear weapons capacity and its considering developing new small nuclear weapons.

"The extremist attitude reflected in these ... practices seems to indicate that no lessons have been learned from the nightmare of Hiroshima and Nagasaki," said Zarif.

"If history is any guide, nuclear weapons, ladies and gentlemen, are in the most dangerous hands," the Iranian ambassador said.