Chechen president Ramzan Kadyrov has ordered his troops to fire at Russian security forces, if they do not have permission to be there, after the killing of a man in Grozny by troops from Russia's Stavropol region.
Mr Kadyrov, who took charge of the republic in southern Russia with the support of Moscow in 2007, maintains his own security forces in Chechnya.
"I would like to officially state: Open fire if someone from Moscow or Stavropol, it doesn't matter, appears on your turf without your knowledge,'' Mr Kadyrov told Chechen security officials. "We have to be reckoned with."
An operation by soldiers from Stavropol led to the killing of a Chechen man in Grozny on 19 April, causing anger in the republic.