(Adds details, weak yen milestone)

By Kantaro Komiya

TOKYO, July 14 (Reuters) - Japan's government is concerned about the yen's recent sharp falls and will monitor the currency market with even more sense of urgency while working closely with the Bank of Japan, Chief Cabinet Secretary Hirokazu Matsuno said on Thursday.

"We are concerned by the yen's rapid declines seen in the foreign exchange market recently," Japan's top government spokesperson Matsuno said, reiterating comments from a number of top policymakers in recent months.

He did not comment on currency interventions.

At a regular news conference, Matsuno also said Japan would keep monitoring the impact of inflation trends and monetary policy changes in the United States on the Japanese and global economy.

Matsuno was answering a reporter's question about the yen's decline on Thursday morning to the 138 yen per U.S. dollar levels for the first time since September 1998, after U.S. annual consumer prices posted the largest increase in more than four decades, raising fears the Federal Reserve may hike interest rates even more aggressively than previously expected.

Meanwhile, the Bank of Japan is expected to maintain ultra-low interest rates at its next July 20-21 meeting, highlighting a growing divergence with a global wave of rate-hiking central banks that has fueled the yen's slump. (Reporting by Kantaro Komiya; Editing by Jacqueline Wong and Kim Coghill)