Birender Singh, minister for labour and employment in the northern state of Haryana, told NDTV news channel that some call centres based in the state were being monitored but there was no blanket ban on women working night shifts.

“Some of the installations do not follow the required rules and regulations of the (labour) department and when it comes to the notice of the department they have to give notice, that is all,”  Singh said.

The norms violated by the call centres “are the safety provisions (for women which is) the prime consideration,” Singh said.

A report in the Times of India yesterday said authorities in Haryana had issued notices to call centres telling them to abide by a 1958 state law that prohibits women from working night shifts.

Haryana state generates a sizeable chunk of the more than five billion dollars India earns every year from call centre work outsourced from countries including the United States and Europe.

Most of the call centres are located in Gurgaon, a town bordering the Indian capital New Delhi.