The Bank of Japan should raise its policy interest rate to “at least around 1 percent” to avoid upside risks to inflation, a board member said Thursday, signaling that the central bank is preparing for further monetary tightening. The comment by the policymaker, Naoki Tamura, came after the BOJ increased the key short-term rate to around 0.25 percent in July from a range of zero to 0.1 percent, boosting it to its highest level in 16 years.