* Gas-directed rig count rises, 2nd gain in 3 weeks * Horizontal rigs climb for third time in 4 weeks * Oil rig count up 12 to 1,397, 1st gain in 3 weeks NEW YORK, Aug 16 (Reuters) - The number of rigs drilling for natural gas in the United States rose by two this week to 388, data from Houston-based Baker Hughes showed on Friday. It was the second gain in three weeks for the gas-directed rig count, which posted an 18-year low of 349 eight weeks ago. Recent rig count gains have stirred concerns that new investment in gas pipelines and processing plants, particularly in the East, are allowing producers to hook up more wells and pump even more supply into an already well-supplied market. Gas futures prices on Friday, which were down nearly 5 cents at $3.37 per million British thermal units just before the data was released, showed little reaction to the report. The oil-focused rig count climbed for the first time in three weeks, gaining 12 rigs to 1,397. The oil rig count hit a nine-month high of 1,413 in mid-June, Baker Hughes data showed. The oil count is down 28 rigs, or 2 percent, from the same week last year. Baker Hughes reported horizontal rigs, the type often used to extract oil or gas from shale, logged their third gain in four weeks, increasing by 12 this week to 1,077. The horizontal count is down almost 10 percent from the record high of 1,193 set in May 2012. Drilling for natural gas has mostly been in decline for the last 22 months. The count is down nearly 59 percent since peaking in October 2011 at 936, but so far production has not slowed much, if at all, from the record high hit last year. The associated gas produced from more profitable shale oil and shale gas liquids wells has kept dry gas flowing at a brisk rate. The U.S. Energy Information Administration still expects gas output in 2013 to hit a record high for a third straight year.