The United Nations nuclear watchdog’s Board of Governors has approved a resolution declaring Iran is not complying with its commitment to international nuclear safeguards, diplomatic sources told Al Jazeera, prompting a swift response from Tehran.

The major step is the culmination of several festering stand-offs between the International Atomic Energy Agency and Iran.

Iran says it has built and will activate a third nuclear enrichment facility, ratcheting up tensions with the U.N. immediately after its atomic watchdog censured Iran for failing to comply with obligations meant to prevent it from developing a nuclear weapon.