Tokyo, June 18 (Jiji Press)--Japanese companies on average found 136.8 yen to the dollar the most desirable exchange rate, a survey by Tokyo Shoko Research Ltd. showed. The Japanese currency has met persistent downward pressure due to the war in the Middle East, hovering at around 160 to the dollar in Tokyo trading Thursday. The gap of more than 20 yen with the desired exchange rate leaves businesses exposed to rising import costs. The online survey, carried out on June 1-8, received responses from about 6,600 companies across the country. Of the respondents, 40.7 pct said that a weak yen has a negative effect on business, overwhelming the 3.2 pct who said it has a positive effect. Wholesalers had the highest proportion of respondents citing negative impacts, at 52.6 pct, followed by retailers, at 49.8 pct. Sectors sensitive to higher purchase costs due to the yen's depreciation topped the list. Japanese authorities are considered to view the 160-yen mark as a line of defense for possible market interventions to prop up the currency. However, 43.4 pct of responding companies said that authorities should intervene at levels below 160 yen. The Bank of Japan's interest rate increase this week has failed to drive the yen higher. The rate hike's effect of curbing the yen's depreciation is "limited because the interest rate gap with Europe and the United States has not narrowed sufficiently," a Tokyo Shoko Research official said. END [Copyright The Jiji Press, Ltd.]