Mauritius is a small country and there is no any industrial development yet. a member of parliament (MP) of India recently said that India's some industrialists and politicians invest their black money in India through Mauritius.
I think you said it all: it is not Mauritius which invests in India, it is rather some Indian citizens who use Mauritius to invest their capital in India. This could be because they are trying to run away from Indian government scrutiny and possible questioning over their source of incomes. Most probably, they are doing so because their funds have been obtained through illicit ways.
..but i think inspite of knowing the open secret government of India has not taken any steps and more specifically there is no any official study/ investigation yet took place to see which section of the population of Mauritius etc are investing their money India. i think a fresh study can be carryout in this direction.