Russia accused the breakaway republic of Chechnya on Monday of making armed incursions across its border and of beheading three men and barbarically displaying their severed heads in a public square.


In a three-day propaganda blitz, the Kremlin appeared to be turning up the pressure on Chechen President Dzhokhar Dudayev, in an effort to bring down the man who led the North Caucasus province's break with Moscow in 1991.


Moscow made public appeals of support for Dudayev's opponents over the weekend, prompting a stinging accusation Monday by a top Chechen official that Russia was preparing to invade the tiny republic, which for three years has defied Moscow's writ.


On a day of looking-glass allegation and counter-allegation Monday, Russian authorities virtually accused the rebel region of a declaration of war. They said Chechen government forces had made sorties into a special security zone in neighboring Ingushetia and North Ossetia, an area where thousands of Russian troops are stationed.


"Provocations have begun by armed groups," said a statement released by the administration in the security zone quoted by Itar-Tass. "Armored cars with armed men have crossed into the emergency zone and a Chechen helicopter has made exploratory flights over strategic sites in the Mozdok region of North Ossetia."


The Interior Ministry kept up the heat when a senior official produced a photograph of three severed heads lying in a street.


Boris Baturin, deputy head of the Interior Ministry's anti-crime department, told a press conference that the three men, whose heads were found on a square in the Chechen capital Grozny on June 13, had helped him in securing the arrest of Chechen hijackers who had fled Russia in May.


A Russian government adviser dealing with Chechnya offered a different version, saying that the heads belonged to opposition fighters killed in a June 13 shootout with forces loyal to Dudayev.


Without alluding to who was responsible, Sergei Filatov, President Boris Yeltsin's chief of staff, said Saturday that the beheadings were indicative of the brutality of the Dudayev regime.


"It has reached the point where heads are being chopped off and displayed on public squares as a form of deterrence," Filatov told Itar-Tass.


Although Moscow's stated policy rules out military intervention, the Russian government hinted it might reconsider that stance Friday when it said in a statement that it might "be forced to defend Russian citizens in accordance with the constitution and the laws of the Russian Federation."


The weekend's events suggest Moscow has given up on rapprochement with Dudayev and decisively thrown its lot in with the Chechen opposition. Umar Avturkhanov, leader of the opposition Provisional Council, was given prime time on Commonwealth television Saturday to appeal for Russia to recognize his movement as the rightful leadership of Chechnya. The newsreader on the same channel told viewers Monday in what sounded like an official statement that "the population of Chechnya basically supports the Provisional Council and hopes that it will become the guarantor of stability in the republic and of relations with Russia."


In reply to the propaganda onslaught, Chechnya's vice president, Zelimkhan Yandarbiyev, accused Russia of "foul lies" and of plotting military invasion of his republic.


Yandarbiyev told The Moscow Times by telephone from Grozny that Russia was behind last Friday's seizure of hostages by a group of Chechens at Mineralniye Vody, in which five people died. He called the incident a "carefully planned operation" organized by Russian intelligence to discredit his republic.


In response to the accusations regarding the severed heads, Yandarbiyev said the three men had been decapitated in a battle on that day but denied the Chechen government was responsible.


Yandarbiyev said Russia has recently deployed thousands of extra troops in the North Caucasus region bordering Chechnya and was planning to intervene.


"We are worried that they will try to move in and spill blood. We are ready for it. If they do it will be a tragedy first of all for Russia," he said.


The only attempt by Moscow to intervene by force in Chechnya, in the fall of 1991, ended ignominiously when an expedition led by then-vice-president Alexander Rutskoi got no further than Grozny airport before turning back. Since then Moscow has mainly tried to use economic pressure on the republic.