India's top court has cancelled 214 of the 218 government permits for coal mines allocated since 1993 after the licensing process was deemed illegal.

"The court has cancelled all the allocations except four," Attorney General Mukul Rohtagi told reporters on Wednesday outside the court.

The Supreme Court of India ruled last month that the country's decades-old method of granting coal mining concessions was illegal and arbitrary, putting investments worth billions of dollars at risk.

The court only spared four blocks despite requests from the federal government to exempt about 40 coal blocks that had either started production or were near it.

The ruling sent shares of Jindal Steel and Power Limited, Hindalco Industries Limited and Tata Power Co Limited sharply lower.

The firms have already spent heavily on steel and power plants based around the coal blocks.

Source: Agencies