** Shares of energy infrastructure co APA group APA.AX rise 6.2% to A$7.020, their highest since January 6

** Stock posts biggest intraday pct gain since April 15, 2020

** Co posts HY underlying EBITDA of A$1015 million ($646.15 million), up 9.1% from last year

** Announces interim distribution of 27 Au cents per share vs 26.5 Au cents last year

** Separately, co announces 5-year plan to expand East Coast Gas Grid to increase north-to-south gas transport capacity

** Stock up 0.7% YTD, including session's moves

($1 = 1.5708 Australian dollars)

(Reporting by Jasmeen Ara Shaikh in Bengaluru)

((Jasmeenaraislam.shaikh@thomsonreuters.com))