Troubled supermarket chain Tesco has reportedly been contacted by private equity buyout company TPG about potentially acquiring Dunnhumby, the data analysis unit that runs its Clubcard loyalty scheme.Dunnhumby, which Tesco bought 10 years ago, has been valued at more than £2bn.According to sources cited by Sky News, the rejected approach was made several months ago but TPG is said to still be interested in potentially making an offer.The news comes amid an investigation into Tesco by the Financial Conduct Authority and Financial Reporting Council, which are examining how the company came to overestimate its first half-year profit by £250m.As part of its own investigation, the grocer on Tuesday asked a fifth senior manager to step aside following the scandal.TPG said it was unable to comment on the matter. Tesco shares were up 1% to 178.45p at 08:56 on Tuesday.