Intensifying its campaign a week before a vote on national unity, the Communist Party on Saturday warned that breaking up the Soviet Union would bring "an atomic cauldron to a boil and incinerate mankind."

Russian Federation President Boris Yeltsin, meanwhile, urged anti-Communists in the republic to unite, saying that March would be a decisive month for democratic forces.Pro-Yeltsin rallies were planned in Moscow and other Russian cities on Sunday, as anti-Communist reformers hoped to turn the March 17 vote into a referendum on the six years of President Mikhail S. Gorbachev's leadership.

The referendum will ask voters "Do you consider it necessary to preserve the Union of Soviet Socialist Republics as a renewed federation of equal, sovereign republics in which human rights and freedoms of any nationality (people of all ethnic groups) will be fully guaranteed?" Voters can answer only "yes" or "no."

Six republics - Latvia, Lithuania, Estonia, Moldavia, Armenia and Georgia - have said they won't hold the vote, although most added they won't block Kremlin loyalists from organizing ballots. The Soviet prosecutor has warned that anyone trying to disrupt the referendum faces prison terms and fines.

The radical newspaper Kuranty reported that Communist Party leaders in various Moscow neighborhoods are organizing groups of war veterans, women and the disabled to fan out among the city's huge blocks of apartment houses to urge people to vote "yes."

Conservative newspapers published an appeal by the pro-Communist Soviet Peace Committee and other public organizations urging a "yes" vote.

"There are no problems that are insoluble by peace efforts, in conformity with conscience and honor in our common home, in the single multi-ethnic family," the plea said. "Let's cast our vote for maintaining the renewed union of equal and sovereign republics."

And in a sharp warning under the headline "The People Have Not Yet Gone Mad," the party newspaper Pravda published an interview with a Soviet lawmaker who warned of nuclear annihilation if the Soviet Union disintegrated into independent republics.

Anatoly Denisov told Pravda that a "no" vote would "destroy a country more than 1,000 years old," and 50 sovereign mini-states, all armed with nuclear weapons, would emerge.

"A veritable atomic cauldron would be brought to a boil on one-sixth of the Earth's surface, mankind would simply be incinerated, and there would be nobody left to bury the ashes," he said.

Those urging a boycott of the referendum in order to dismantle the Soviet empire are "out to seize power at all costs," Denisov said.