About 400 city and national political, civic, religious and business leaders yesterday endorsed a plan to add the District to the growing list of jurisdictions voting this year on a proposed freeze on nuclear weapons.

"Every human being should know that if we have a nuclear war . . . We will all be gone," said council member Hilda Mason (Statehood At-Large), a member of the newly formed D.C. Campaign for a Nuclear Weapons Freeze, which will attempt to place the issue on the Nov. 2 ballot.

The group wants voters to approve a measure recognizing prevention of nuclear war as the only defense against nuclear destruction and calling on the United States and the Soviet Union to freeze production of nuclear weapons and redirect arms monies to human needs.

Similar efforts are now underway in California, Montana, Michigan, New Jersey and Delaware.

At a District Building press conference attended by about 50 supporters, the group listed among its backers Mayor Marion Barry; 11 of 13 City Council members including chairman Arrington Dixon; D.C. Delegate Walter Fauntroy; five school board members including president David Eaton; businessman John W. Hechinger and the Right Rev. John T. Walker, Episcopal Bishop of Washington.

Barry Israel, a Washington attorney and member of the campaign's steering committee, said the group believes it may need to spend up to $75,000 to get the initiative approved by the voters. Organizers said they have about $400 on hand.

The initiative is scheduled for review by the city elections board April 7. If it meets the city's legal requirements, the group could begin gathering the 14,500 signatures of registered voters that would be required to place the measure on the ballot.

Barry did not attend yesterday's press conference. City officials present included council members Mason, David A. Clarke (D-Ward 1), Polly Shackleton (D-Ward 3) and Betty Ann Kane (D-At Large), who called nuclear weapons "an equal opportunity destroyer."

A freeze campaign spokeswoman said council member H.R. Crawford (D-Ward 7) decided not to endorse the effort "at this time" and the Rev. Jerry A. Moore (R-At Large) did not respond to the group's solicitation.

Voters in 155 of 185 town meetings in Vermont have endorsed the freeze concept. The Loudoun County commissioners earlier this month made it the first jurisdiction in the metropolitan area to approve the freeze campaign, though they are now under some pressure to reconsider. A bill also is pending in the Maryland legislature.