BANKERS SEE SHARP RISE IN THAI FOREIGN RESERVES Thailand's improving economy will likely cause foreign reserves to increase to at least five billion dlrs by end-1987 from a record of nearly 4.2 billion at end-February, private bankers said. Bank of Thailand statistics show foreign reserves rose to 3.95 billion at end-January from 3.03 billion a year earlier. Nimit Nonthapanthawat, chief economist at the <Bangkok Bank Ltd>, said Thailand's strong export performance, its relatively high interest rates, foreign participation in its stock market, and growing foreign investment, especially from Japan, contributed to the projected sharp rise. Thai exports rose 19.4 pct in 1986 and are expected to expand another 15 pct this year, bankers said. A U.S. Embassy report said last month Thailand could achieve five pct real gross domestic product growth in 1987, up from a projection of 3.8 pct for 1986 and 3.7 pct in 1985. Nonthapanthawat said if economic growth continues at its current pace and oil prices and major currencies remain stable the five billion 1987 reserves target can easily be reached. Thailand calculates foreign reserves to include gold, special drawing rights and convertible currencies. The target is equivalent to five-and-a-half months' worth of imports.