Ghaziabad, June 16 (IANS): At least a dozen workers at a factory here were critically injured when ammonia gas leaked out from the unit's refrigeration plant on Tuesday, police said adding that six of those affected fell unconscious.

The affected workers -- from the Sahibabad-based meat processing unit of Allana Frigorifico Ltd -- were rushed to hospital, where doctors said their condition was critical.

Police said the ammonia gas leak from the refrigeration plant of the meat processing unit was first noticed around 12.30 p.m. The workers started feeling nauseous and at least six of them fell unconscious.

The management immediately rushed them to the nearby Vasundhara Hospital, where five patients were admitted to the Intensive Care Unit (ICU).

Some of those affected were discharged after being administered first aid. Among those undergoing treatment at the ICU were Chandni, 19, Tahir, 18, Kajal, 22, Sultana, 19 and Ram Laxmi, 18, police said.

"Some of the patients have partially recovered but they can still not be said to be out of danger," said R.S. Kasana, a doctor at Vasundhara Hospital.

"Ammonia gas has a pungent smell and is corrosive. On being inhaled, it causes nausea and can damage the lungs," said the doctor.

"We have registered a case against two officials of the company for negligence," said Rashid Ali, Inspector of Link Road police station.