Emergency services are currently at the scene of a commercial premise in Pontyfelin Industrial Estate, New Inn, Pontypool.
A multi-agency response is underway following a report of substance leak (ammonia) within a commercial premise shortly before 8am.
The building was evacuated earlier this morning and all staff are accounted for.
No injuries have been reported.
Local residents are being advised to avoid the area at this time and to please keep windows and doors closed as a safety precaution.
The A4042 between the Rechem roundabout and New Inn (both directions) is closed and will be for some time.
Updates to follow.