A Williamsburg summit, Soviet style, is planned

The Soviet Union is planning a summit meeting in Moscow of Communist Party leaders from the seven-nation Warsaw Pact next week, East European sources said Wednesday.

The meeting, planned as a Communist reply to the seven-nation ''capitalists' summit'' in Williamsburg, Va., last month, is expected to concentrate on medium-range nuclear arms in Europe. The sources said the agenda for the meeting , due on Tuesday, had not been set. They said it was still possible the project might fall through if Romania, Moscow's most independently nationalist ally, objected.