TEHRAN: Iran agreed Wednesday to allow a UN watchdog the access it has requested to two alleged nuclear sites, as the head of the agency ended his first visit to Tehran.

The announcement came only hours after Iran's arch foe the United States suffered a humiliating defeat when the United Nations blocked its controversial bid to reimpose international sanctions on the Islamic republic.

The US move had threatened to torpedo a historic 2015 accord under which Iran had agreed to curb its nuclear programme in exchange for sanctions relief.