SINGAPORE (Bloomberg) Exports from Asia's developing economies may decline 20 percent over the next year as a deepening global slowdown hurts demand for the region's products, according to Nomura International (HK) Ltd.

"In September 2008, aggregate exports for Asia ex-Japan grew by 21 percent year on year," Robert Subbaraman, an economist at Nomura in Hong Kong, wrote in a report released Thursday. "In 12 months time, we would not be surprised if the number is about the same, but with a negative sign in front of it."

Exports from Asia's emerging economies have held up until recently, as shipments to other destinations made up for weaker sales to the United States. That's changing as the economic downturn becomes "global and synchronized," and a slump in commodity prices erodes incomes in oil-producing nations, Subbaraman said.

China's exports grew at the slowest pace in four months in October, with overseas shipments rising 19.2 percent from a year earlier, after increasing 21.5 percent in September.

South Korea's overseas sales, which account for more than half of gross domestic product, rose 10 percent in October from a year earlier — the weakest pace in 13 months.