Southwestern Russia's Chechnya region will ask federal authorities to demarcate an administrative border between Chechnya and Ingushetia, saying its lands are being seized.
The issue was discussed at a meeting between Chechen leader Ramzan Kadyrov and regional officials.
The meeting discussed that officials in Ingushetia "undertake measures not only to legally settle in territories which the Chechen authorities considered the borderland between the two republics, but also to seize new lands, encroaching on the territory of the Chechen republic," said a statement posted on the Chechen government website.
Kadyrov said: "I will raise the issue of delimitating the administrative border between the republics at the federal level. If two republics, two federal entities are now separate, they should have a clear border between them."
"This is vital for economic activities, taxation, law-enforcement and nature conservation efforts," Kadyrov said.
"Whole villages and districts have been seized (by those) taking advantage of the Chechen people's problems. We showed restraint. But the process to seize more and more Chechen territories is underway. We will not allow any jokes," Kadyrov said.
"These actions are provocative by nature. The boundary line, which we have never drawn and in which we took no interest, is being pushed inside the Chechen Republic," he said.
The Chechen-Ingush Autonomous Soviet Republic, a single administrative entity in the Soviet Union, split in December 1992.
According to the statement, Ingush officials "refer to documents allegedly signed by (Chechen separatist leader) Dzhokhar Dudayev".
Dudayev became president of the newly declared Chechen Republic in October 1991 and declared independence from Russia the following month. He was killed in 1996 by a Russian-fired precision-guided bomb.
"If the Russian laws and the Russian leadership see the Dudayev regime as illegal, all his agreements, decrees and ordnances are also illegal. If some borderline-related documents are considered lawful, then we will have to admit the legitimacy of Dudayev and his criminal regime," Kadyrov said.
Ingush officials were not available for comment.