SEOUL, Oct 20 (Reuters) - LG Electronics Inc , the world's No. 4 mobile phone maker, said on Monday it sold 23 million mobile phones in the third quarter, down from 27.7 million units in the second.

Its operating profit margin from mobile phones also dropped to 11.5 percent, from 14.4 percent in April-June.

LG's display unit, which makes plasma screens and flat-screen TVs, posted an operating margin of 0.4 percent against 1 percent in the second quarter. (Reporting by Kim Yeon-hee and Park Ju-min; Editing by Keiron Henderson)