Zurich, March 27 (Bloomberg) -- The Swiss National Bank said it lowered its daily repo, or repurchase, rate by 10 basis points to weaken the value of the Swiss franc against the euro. ``The recent sharp rise of the franc against the euro is unfounded,'' central bank spokesman Werner Abegg said. The SNB said it's concerned about gains in the Swiss currency because it hurts exports, which account for about 45 percent of the Swiss economy. The countries that share the euro buy more than half of all Swiss goods. The Swiss currency fell to 1.4657 francs per euro from 1.4636 yesterday. On Monday, the franc climbed to a four-month high. The SNB kept its target band for three-month Libor unchanged at 1.25 percent to 2.25 percent but said it will ``use the room it has to maneuver'' to steer market rates lower.