The Aditya Birla Group has begun a due diligence exercise of Nalco that it is bidding for. The group is in the race for the PSU along with Sterlite Industries and 12 other foreign companies. While officials in Hindalco Industries, the group's flagship and the country's largest aluminium company, said they were still evaluating who to team up with for Nalco, the due diligence will be done by the group itself. The group has kept its option of tying up with a foreign partner open. Market sources have indicated that chances of Alcoa being a possible partner have come down greatly due to differences of opinion between the two. The group had earlier agreed with Alcoa to jointly bid for aluminum projects in India and abroad and had even initially pitched for the disinvestment of the government stake in Balco. The two now do not share the same arrangement.