As Lakshmi Mittal's rise to global business prominence has gathered pace over the past decade, the Indian steel magnate has had a lot to smile about. But in recent days, he has been far from cheerful, in the wake of a serious accident in his company's Kazakhstan operations that killed 30 people.

The blast in the Abaiskaya coal mine run by ArcelorMittal - of which Mr Mittal is chief executive and main shareholder - is the latest in a series of accidents in Kazakhstan that has led to 191 deaths since the company started operating in the country in 1996.