TAIPEI, Jan 15 (Reuters) - Taiwan’s central bank began meeting this week with major exporters to ask them to spread out sales of foreign currency, four sources with direct knowledge of the matter told Reuters, as it continues to try to rein in the soaring local currency. The Taiwan dollar’s 5.6% gain against the greenback last year was among the strongest in Asia and its rise extended it to a fresh 23-1/2-year high of 27.938 per dollar on Wednesday. It is up nearly 2% this year. (Reporting by Liang-sa Loh; Writing by Ben Blanchard; Editing by Jacqueline Wong)