The nation is emerging from its economic lull on the back of improving overseas economies, the Bank of Japan said Tuesday, upgrading its assessment for the first time in nine months while maintaining its ultra-loose monetary policy.

The assessment that the economy is "gradually emerging from the current deceleration phase" suggests that the BOJ expects the economy to exit from the pause possibly in the January-March period, although data Monday showed contraction in the three months through December for the first decline in five quarters.

On monetary policy, the BOJ left its key interest rate unchanged in the range of zero to 0.1 percent at its two-day policy meeting and maintained the size of its asset purchasing program at ¥5 trillion, under which the bank buys assets ranging from government bonds to riskier exchange-traded investment funds to pump money into the financial system.

"As the growth rate of the global economy has started increasing again led by emerging and commodity-exporting economies, Japan's exports and production are showing signs of resuming an uptrend," the BOJ said in a statement.

The recovery has been leveling off from last fall amid the diminishing effects of fiscal stimulus measures designed to boost consumer spending.

The BOJ's nine-member Policy Board said following its previous meeting in late January that the economic recovery "seems to be pausing" as exports were "somewhat weak" and production "declined slightly."

The contraction of preliminary GDP in the October-December period added to evidence the recovery was at a standstill.