At the Dec. 19-20 meeting, the BOJ kept its ultra-easy monetary policy but shocked markets with a surprise tweak to its bond yield control that allows long-term interest rates to rise more.

Under law, two government representatives - one from the Ministry of Finance and another from the Cabinet Office - can attend BOJ policy meetings and voice the government's views on policy decisions, though they cannot cast votes.

The representatives likely requested the adjournment to contact their ministries on how they express the government's view on the BOJ's decision to tweak yield curve control.

(Reporting by Leika Kihara; Editing by Kim Coghill)