The opposition Liberal Party has worked out a draft proposal for revising the Constitution to allow Japan's Self-Defense Forces to participate in all types of U.N. peacekeeping activities, party sources said Sunday.

The draft, the first comprehensive proposal on amendments to the Constitution by a Japanese political party in recent years, is likely to be officially endorsed by the party Dec. 13, they said.

The draft, titled "A basic idea for creating a new Constitution," says the amended Constitution should stipulate the terms of the SDF's authority and its duties.

Under the proposed Constitution, the SDF would be allowed to use force only to counter an invasion. The draft does not stipulate if the SDF would be allowed to use force if required during peacekeeping operations.

At present, the SDF is banned from participating in some U.N. peacekeeping tasks -- such as monitoring demilitarized zones -- because they may put SDF members in a position requiring force, in violation of the Constitution.

Article 9 of the Constitution -- which renounces the use of force as a means of settling international disputes -- should be maintained in the amended document with a new call for a thorough U.N. collective-security system and a U.N. police force, the proposal says.

The draft says the new Constitution should aim to create a free and creative Japan, and should keep the Emperor's status as the "symbol of the state and the unity of the people" intact.

The draft calls for education to foster the "traditional Japanese nature" to make the next generation "good Japanese."