The Justice Ministry will propose major law revisions to grant criminal liability immunity to people cooperating in police investigations, ministry officials said Thursday.

The revisions will also enable law enforcement authorities to introduce a charge of conspiracy currently not stipulated in the Criminal Code.

The proposed changes are aimed at boosting cooperation in cracking down on international crime, especially related to the mafia and yakuza, and would bring Japanese investigative procedures more in line with Britain and the United States.

Among the laws under revision is legislation enacted last summer to crack down on organized crime.

To combat crimes such as smuggling and drug trafficking, the U.S. and other countries want Japan to beef up its cooperation with investigative organs overseas.

This year, a global treaty for strengthening countermeasures against international crime is expected to be endorsed by the U.N. General Assembly. Japan plans to ratify the pact.

After receiving endorsement from an advisory panel to the justice minister, the ministry will submit the amendments to the Diet possibly within next year, officials said.

One of the points of dispute in the amendments is expected to be the scope of immunity for suspects or criminals cooperating in investigations and of the proposed conspiracy charge, according to the officials.

In the Lockheed payoff scandal of the 1970s, in which former Prime Minister Kakuei Tanaka was found guilty, Japanese investigators received evidence from Carl Kotchian, then vice chairman of Lockheed Corp., and others in exchange for immunity from prosecution.

The Supreme Court ruled that the Constitution did not rule out the introduction of an immunity-for-evidence method of investigation.

The Criminal Code has so far regarded those who have actually carried out any act in relation to a crime as a conspirator, but the amendments will make it possible to also charge those who conspired in any way with the perpetrators.

In the U.S., a charge of conspiracy has been widely applied in order to have a Muslim fundamentalist suspected of masterminding the bombing of U.S. embassies in Africa put on the wanted list.