Vedanta Resources has raised its offer for the purchase of Asarco, the bankrupt US copper miner, by $500m (£299m) – for a total of almost $2.6bn – in a bid to wrest the group from a rival offer by Grupo Mexico and diversify its operations beyond its base in India.

The total value of the offer made by Sterlite Industries, a subsidiary of Vedanta, stands at $2.57bn, close to the original $2.6bn bid made by Sterlite in May last year, before a fall in the copper price led it and Grupo Mexico to revise offers downwards.