UN Secretary-General Ban Ki-moon was unharmed but ducked behind the podium after a rocket landed near Prime Minister Nouri al-Maliki's office Thursday while the two men were speaking to reporters at a news conference.
An Associate Press reporter ran outside and saw a crater one-meter (yard) in diameter about 50 meters (yards) from the building where the news conference was in progress.
Al-Maliki security officials said it was a rocket attack.
Small chips of debris floated down from the ceiling above the UN chief after the big explosion rattled the building in the Green Zone.
Al-Malik said "nothing's wrong" as one of his security men started to grab the prime minister. Within minutes the two men resumed their news conference.
The sound of the weapon being fired could be heard not far from The Associated Press office, which is across the Tigris River to the east of the Green Zone, which also houses the US Embassy and Iraqi government offices.