SEOUL, July 23 (Reuters) - Hyundai Motor 005380.KS reported a 21% fall in second-quarter operating profit on Thursday, missing analysts' estimates, as weaker vehicle sales, production disruptions and higher costs outweighed support from a weaker won.

Hyundai, which together with affiliate Kia Corp 000270.KS is the world's third-biggest automaking group by sales, posted operating profit of 2.9 trillion won ($1.98 billion) for the April-June period, compared with 3.6 trillion won a year earlier.

That compared with a 3.2 trillion won forecast by LSEG SmartEstimate, which is weighted toward analysts who are more consistently accurate.

($1 = 1,467.2000 won)