The ruling and opposition parties locked horns over the Trans-Pacific Partnership free trade agreement on Tuesday, kicking off Diet deliberations on ratifying the pact. It is likely to be the predominant focus of debate until June, when this ordinary Diet session ends.

In a question-and-answer session, the Democratic Party and the Japanese Communist Party denounced the pact as unworthy of deliberation.

They pummeled the government, apparently with an eye on the Upper House election this summer, arguing that the government has underestimated the likely economic damage from TPP to the nation's agriculture and fisheries industries. They said it also has failed to disclose information about how the negotiations took place.