Japan's Chief Cabinet Secretary Yoshihide Suga attends a Thomson Reuters Newsmaker event in Tokyo, Japan August 30, 2016. REUTERS/Kim Kyung-Hoon

TOKYO(Reuters) - Japan’s cabinet on Tuesday approved legislation that would penalize criminal conspiracies, a move critics say threatens civil liberties, but officials say is needed to prevent terrorist targeting events like the 2020 Tokyo Olympics.

Proponents say the steps are vital in a security climate where terrorism risks have grown and in order to ratify a U.N. Treaty aimed at battling international organized crime.

“Considering the current situation regarding terrorism and looking ahead to the Olympics and Paraolympics three years hence, it is necessary to fully prepare to prevent organized crimes including terrorism,” Chief Cabinet Secretary Yoshihide Suga told a news conference.

Japanese governments have tried to pass similar legislation three times since 2000, when the United Nations adopted a Convention against Transnational Organised Crime, but the bill stands a better chance of success this time.

Prime Minister Shinzo Abe’s ruling coalition has a two-thirds majority in both houses of parliament and public worries about terrorism ahead of the Olympics have grown after deadly attacks overseas, although an opinion poll released by Kyodo news agency on March 12 showed 45.5 percent were opposed to the bill while 33 percent favored it.

Suga said the legislation would apply only to groups preparing to commit terrorist acts and other organized crime groups and would not target the “legitimate activities” of civil groups or labor unions.

Opponents, including the Japan Federation of Bar Associations, have doubts. They view the proposed change as part of Abe’s agenda to tighten control at the expense of individual rights, chilling grassroots opposition to government policies such as the construction of a U.S. military base on Okinawa island.

“It is very clear that the Japanese public security sector – police and prosecutors – employ an extremely expansive interpretation of any aspect of criminal law so ... regardless of the limited list of potential crimes, they will interpret it in an extremely elastic way,” said Lawrence Repeta, a law professor at Meiji University in Tokyo.

The lawyers’ association has said Japanese law already prohibits preparations to commit certain serious crimes such as murder, arson and counterfeiting or plotting an insurgency or the use of explosives, so additional legislation is unnecessary.