Nine workers who suffered carbon monoxide poisoning at a plant nursery have been discharged from hospital.

It has also emerged the company which runs the Nazeing site, MBJSC Produce, had previously received notices for failing to provide health and safety information to non-English speaking employees in a manner they could understand.

Emergency services were called to Tylers Cross Nursery, which stores vegetables, in Epping Road at 9.53am yesterday following reports of staff suffering from chest pain, sickness and dizziness.

Three of the more seriously affected were taken to Whipps Cross Hospital in Leytonstone for treatment in a hyperbaric Chamber.

Six others were taken to Princess Alexandra Hospital in Harlow as a precaution.

Tests carried out by the fire service revealed a high level of carbon monoxide in a storage area caused by a leak from a refrigeration unit.

The enforcement notices were issued to MBJSC Produce in 2010 and 2011.

The company said regulations are now complied with, but refused to say whether the staff members affected were foreign nationals.

A spokeswoman said: “The site is safe. We take care of our staff and I am so glad they are ok.”

An investigation into the cause of the leak is continuing.

The Health and Safety Executive has confirmed they are aware of the incident and is working with the Fire Brigade to make inquiries before any official investigation is launched.

An earlier version of this story incorrectly used a photograph of another nursery, MP Salads. We are happy to clarify MP Salads has no connection with this incident.