Prime Minister Shinzo Abe on Monday opened a 66-day extraordinary Diet session with a policy speech that pledged additional fiscal measures to prop up the economy while also urging opposition parties to dig into the hornet's nest of debate over revising the Constitution.

The government last month unveiled a ¥28 trillion stimulus package, ¥4.1 trillion of which comprised a supplementary budget.

The Diet is expected to endorse the extra budget and debate ratification of the Trans-Pacific Partnership free trade agreement during the session, which runs through Nov. 30.