UPDATE 1-Oil prices fall as economic growth worries spread * China's 2018 GDP growth at lowest since 1990 * South Korea's economic growth slows to a 6-year low * IMF downgrades 2019 global growth forecast * OPEC-led supply cuts support crude prices (Adds South Korea GDP data, quotes, updates prices) SYDNEY/SINGAPORE, Jan 22 (Reuters) - Oil prices fell on Tuesday as signs of a spreading global economic slowdown stoked concerns over future fuel demand.International Brent crude oil futures were at $62.26 per barrel at 0410 GMT, down 48 cents, or 0.8 percent, from their previous close.U.S. West Texas Intermediate crude futures were at $53.44 per barrel, down 0.7 percent, or 36 cents. China on Monday reported its lowest economic growth figure since 1990, with GDP rising by 6.6 percent in 2018. manufacturing activity in China is likely weighing on demand," said Singapore-based tanker brokerage Eastport on Tuesday, adding that industrial slowdowns tended to be leading i