More than 50 women workers of an apparel manufacturing unit in the Brandix Special Economic Zone at Atchyutapuram near here fell sick on Tuesday due to what was suspected to be a mysterious gas leak, the second such incident in two months.

The real cause of the sickness was, however, not immediately established as medical examination was being conducted.

While some of the workers were administered first aid in the medical centre in the SEZ, some others were shifted to nearby hospitals, police sources said.

Some of the workers who fell sick were said to be pregnant.

On June 3 too a similar incident occurred in the same place where more than 200 women workers fell unconscious after complaining of eyesore, nausea and vomiting.

It was then suspected that ammonia gas leaked from a nearby Porus Laboratories unit.

A team of experts from the Indian Institute of Chemical Technology in Hyderabad visited the lab and conducted tests to determine the cause of the leak while the AP Pollution Control Board ordered closure of the lab.

The Porus lab was shut down for a few days after the mishap but soon resumed activities.

Against this backdrop, the fresh incident happened, triggering panic among the workers in the SEZ.

On Tuesday too the women workers had nausea and vomiting.

The Brandix SEZ employs thousands of workers, mostly women, in the garment manufacturing units.