Ruling and opposition parties agreed Wednesday to briefly reopen both houses of the Diet on Monday for one-off committee deliberations, with plans to quiz a former top education ministry bureaucrat who alleged favoritism by Prime Minister Shinzo Abe.

The agreement came after the main opposition Democratic Party spurned an offer by the ruling Liberal Democratic Party for committee deliberations next Monday or Tuesday, on the grounds that Abe would be unable to attend due to an overseas trip.

"The prime minister not attending is equal to hiding him," DP policy chief Hiroshi Ogushi said Wednesday. "The government doesn't seem to be taking the issue seriously."