SERZHEN-YURT, Chechnya -- Amid reports that the Kremlin had approved a ground invasion and that armor had already rolled 10 kilometers into Chechnya, Grozny warned on Thursday it was ready to take the war to Russian territory.


Russia stepped up airstrikes as well, hitting a road used by refugees, a brick factory, a collective farm and, again, the Grozny oil refinery.


President Boris Yeltsin's deputy chief of staff, Igor Shabdurasulov, was cited by Interfax as saying that a Defense Ministry plan for a ground invasion had been approved.


Prime Minister Vladimir Putin, meanwhile, repeated that federal troops had seized key heights inside the Chechen-Dagestani border.


Thursday's bombing began at 4 a.m. in the Itum-Kalinsky region, where attack jets targeted - for the third day in a row - a mountain road along which refugees were fleeing to the border with Georgia. At 11 a.m., a broader wave of airstrikes hit targets all across Chechnya and continued with brief intervals for the rest of the day.


Fires blazed at oil wells north of the capital, Grozny. A brick factory at Shali, southeast of the capital, was also hit, with injuries reported among the workers. A noontime attack struck a collective farm in the Serzhen-Yurt area, destroying a large barn and killing two civilians, while more bombs fell south of Grozny in the late afternoon.


Information on casualties was spotty due to the lack of telephone communications through Chechnya, but the Chechen government said that at least six people had been killed and 10 injured.


Russia has been bombing Chechnya for eight days and has massed tens of thousands of troops on the Chechen border.


Russian tanks advanced 10 kilometers into Chechnya in the Naursky district north of the Terek River, but later pulled back 5 kilometers, according to a statement from the headquarters of Chechen President Aslan Maskhadov.


According to Chechnya's representative office in Moscow, Russian ground units crossed the border into both the Naursky and Shelkovsky districts, which make up the flatlands in northern Chechnya.


The Naursky district runs from Chechnya's border with Russia's Stavropol region in the north to the Terek River in the south. The Shelkovsky district runs from the Dagestani-Chechen border in the north to the Terek River. Various media have predicted that in the first stages of a ground attack, Russian forces plan to seize the two districts and then use the river as a natural boundary to blockade Chechnya.


Russian military officials are neither confirming nor denying the reports.


Chechen Defense Minister Magomed Khambiyev said on state television that if Russia invaded, "specially prepared detachments of the Chechen army will operate in the rear of the Russian forces, on the territory of Russia."


The Russian strikes are a response to the seizure of villages in neighboring Dagestan in August and September by Chechen-led rebels seeking to establish a separate Islamic state. They are also Russia's answer to a string of terrorist bombings that have killed about 300 people since Aug. 31. The government blames the bombings on Chechens, though the Chechens deny responsibility.


Thousands of people fleeing the bombings were encamped near the border with Ingushetia, where border guards were extorting bribes to cross. They demanded $200 for a truck full of refugees, and 2,000 rubles ($80) for a small passenger car.


Akhmed Malsagov, head of the government in Ingushetia, told Reuters that 63,829 refugees had been officially registered by the authorities in the tiny republic by Thursday morning. He said refugees were still crossing at a rate of 5,000 to 6,000 a day.


The European Union expressed alarm at the intensification of hostilities and urged Russia not to launch a full-scale invasion. "Military escalation would cause huge civilian casualties," the 15-nation bloc said in a statement released by its current president, Finland. "The EU is urging the Russian government to reopen a dialogue with moderate political forces in Grozny."


It wasn't clear, however, what there was to negotiate since Maskhadov does not control the armed bands of warlords Shamil Basayev and Khattab.


Foreign Minister Igor Ivanov said in Belgium that Chechnya was an internal Russian matter, Reuters reported.


"We think it is very important that in Italy, France and Germany they understand the complexity of the situation. It is very important that in Rome, Paris and Berlin they look on this as an internal Russian problem," Ivanov said.


"As concerns the civilian population, I want to say that this problem is an even greater concern for the Russian leadership, which has taken and is taking all the necessary measures so that the legal fight with terrorism has fewer consequences for the civilian population," he said.


Yeltsin was paying close attention to the situation, said his spokesman, Dmitry Yakushkin.


"The president is carefully following every aspect of the situation, military and humanitarian, not only in Chechnya but also in neighboring regions," Yakushkin said.


Yeltsin has stayed out of public view and said little publicly since the fighting began.


Russian forces launched a disastrous invasion of Chechnya in mid-December 1994 to quell a secessionist movement.


Russian troops were driven out in 1996 after 80,000 people died, most of them civilians or untrained Russian conscripts. Since then, Chechnya has run its own affairs, but no other other country has recognized its independence.