TOKYO (Reuters) -Japan's Honda Motor posted a 31% increase in operating profit for the September quarter on Thursday, lifted by stronger sales in the United States and a weaker yen, and raised its full-year forecast by 20%.

Japan's second-biggest automaker by sales said operating profit totalled 302.1 billion yen ($2.0 billion) in the three months to Sept. 30, compared with an average 345.3 billion yen estimate in a poll of 10 analysts by LSEG.

Like its rivals, Honda has benefited from a weak yen and solid U.S. sales, which helped offset decreasing sales in China, where it faces growing price competition.

Honda raised its full-year operating profit forecast to 1.2 trillion yen from the 1 trillion yen it had expected, largely in line with the 1.237 trillion yen average forecast from 21 analysts.

($1 = 151.0600 yen)

(Reporting by Daniel Leussink; Editing by David Dolan and Gerry Doyle)