Aug 23 (Reuters) - Britain"s competition regulator said on Monday it has started its investigation into whether business information provider S&P Global"s (SPGI.N) $44 billion purchase of London-based peer IHS Markit Ltd (INFO.N) would hurt competition. S&P Global last year agreed to buy IHS Markit, creating a new data powerhouse serving Wall Street and the corporate world. The Competition and Markets Authority said it has set a deadline of Oct. 19 for its phase 1 decision. The regulator had invited comments from interested parties in June.