* Sept exports seen +14.9 pct yr/yr vs +18.1 pct in Aug
* Imports f'cast +15.0 pct, trade surplus at 559.8 bln yen
* Trade data due 2350 GMT Wednesday
TOKYO, Oct 13 (Reuters) - Japan's exports likely grew for a tenth straight month in September buoyed by upbeat demand from overseas, a Reuters poll showed on Friday, underscoring a steady economic recovery.
Exports were seen up 14.9 percent in September from a year ago, following a 18.1 percent jump in August, the fastest pace of increase in nearly four years, the poll of 18 economists showed.
Imports are forecast to have risen an annual 15.0 percent, climbing for nine months in a row, the poll found.
As a result, Japan likely posted trade surplus of 559.8 billion yen ($4.99 billion) in September, which would be the fourth straight month in the black.
Japan's export sector has been supported by a surge in demand for the country's cars and electronic devices, particularly semiconductors and electronic displays.
"Exports continue to be upbeat, notably shipments to Asia and the United States," said Akihiro Morishige, senior economist at Mitsubishi Research Institute.
"Export growth of capital goods such as semiconductor manufacturing equipment is remarkable because the global demand for semiconductors is on the rise."
Positive data could help Prime Minister Shinzo Abe ahead of an Oct. 22 election as he tries to convince voters that his "Abenomics," a policy mix of ultra-lose monetary policy and huge fiscal spending, helped improve the economy.
The finance ministry will release the trade data at 8:50 a.m. Tokyo time on Thursday (2350 GMT Wednesday).
Japan and the United State will hold the second round of an economic dialog on Oct. 16 in Washington.
At the talks, Tokyo is expected to propose changes to its safeguard mechanism on frozen U.S. beef imports, which has been a point of U.S. criticism in its trade dialog with Japan.
If successful, the proposal could help ward off trade friction with the United States, which is renegotiating free trade agreements with other countries to protect jobs and lower its trade deficit. ($1 = 112.1300 yen) (Reporting by Kaori Kaneko; Editing by Sam Holmes)