South Korea's antitrust regulator has fined Alphabet Inc's Google 207 billion won (US$176.64 million) for blocking customised versions of its Android operating system (OS), in the US technology giant's second setback in the country in less than a month.

The Korea Fair Trade Commission (KFTC) said on Tuesday Google's contract terms with device makers amounted to an abuse of its dominant market position that restricted competition in the mobile OS market.