(Adds Brazil steel association comment, additional output numbers)
SAO PAULO, Oct 19 (Reuters) - Brazil's steel output rose in September, the first year-on-year gain in 15 months, a possible sign that the worst part of a downturn affecting the industry may be over, the Brazil's steelmakers' association, Instituto Aço Brasil, said on Wednesday.
Production rose 3.1 percent in September to 2.58 million tonnes compared with the same month a year earlier. Production, though was down 6.8 percent compared to August, the association said in a statement.
September domestic steel sales were little changed, falling 1.3 percent to 1.47 million tonnes. Sales fell 0.8 percent from August.
"The intensity of declines in industry indicators has been falling. We can't say if we've reached the turn-around point, but from the reaction of the indexes, we can say the worst is probably over," said Marco Polo de Mello Lopes, president of the association.
Brazil's steel industry is operating at about 60 percent of its built capacity of 49 million tonnes of raw steel a year, Lopes said. The sector is expecting Brazil's recession-mired economy to rebound next year allowing it to boost output to 75 percent to 80 percent of capacity, he added.
Meanwhile, September exports fell 13.1 percent to 1.35 million tonnes, and imports fell 8.2 percent to 205,900 tonnes.
By value, exports fell 8.9 percent to $620 million and imports fell 15.7 percent to $158 million. (Reporting by Alberto Alerigi Jr; Writing by Jeb Blount; Editing by Meredith Mazzilli and Sandra Maler)