President Barack Obama and Iranian Foreign Minister Mohammad Javad Zarif shook hands at the United Nations, an Iranian official told Reuters on Tuesday, adding that the historical event on Monday "was not preplanned".

"It was kind of accidental and happened after (President Hassan) Rouhani's speech to the UN General Assembly on Monday," said the senior official on condition of anonymity.

"Nothing was planned at all, and it just happened in a few seconds and they greeted each other as well."  - Reuters