(Reuters) -Britain's antitrust watchdog said on Wednesday it is looking into whether Vodafone and CK Hutchison's $19 billion tie-up to create the country's biggest mobile operator would lead to substantial lessening of competition.

The Competition and Markets Authority (CMA) said it has invited comments from interested parties on the deal, which was announced in June.

When the deal was announced, it was poised to face regulatory scrutiny. Seeking to win over politicians, unions and the competition authorities, the two groups had said they would invest 11 billion pounds to create "one of Europe's most advanced standalone 5G networks".

(Reporting by Eva Mathews in Bengaluru; Editing by Nivedita Bhattacharjee and Savio D'Souza)