India’s national carrier Air India is set to ground 125 “overweight” cabin crew members.

An Air India official told the BBC that the order had been made on the basis of a document issued by the civil aviation authority last year.

The airline had warned 600 of its crew to “shape up” last year, but 125 had not managed to maintain the required weight, the official said.

The airline says however that the issue is not one of weight, but “fitness”.

Airline officials confirmed to the BBC that the directive had been issued, but said it was part of an internal document which they could not comment on publicly.

They said the basis for the recommendation was concern that “unfit” cabin crew would not be able to operate efficiently in emergency situations.

Aviation regulations state that a Body Mass Index (BMI) of 18-25 is normal for a male cabin crew member, while for a female it is 18-22.

Aviation expert Kapil Kaul told the BBC: “An overweight crew is a signal the airline is not fit. You need a smart friendly agile crew that can complement the image of the airline.”

However, national union leader Tapan Sen denied that service rules mention any firm weight restriction for cabin crew.

This is not the first time Air India has grounded staff over weight issues. In 2009, it dismissed nine hostesses for being “overweight” on safety grounds saying their shape could “impair agility”.