Moscow (AFP) - Chechen leader Ramzan Kadyrov on Thursday ordered his troops to "shoot to kill" if they encountered any unauthorised Russian forces on the territory of the small republic in the volatile North Caucasus region.

"I am officially stating that if (a soldier) appears on your territory without authorisation, whether he comes from Moscow or Stavropol, shoot to kill," the Kremlin-loyal strongman said in a video broadcast by the local Grozny TV station. "They need to take us into account," he added.

Kadyrov appeared to be speaking at a gathering of representatives of the special forces in the mainly Muslim autonomous region, where separatists fought two wars against Russia in the 1990s.

"We don't have the right to leave our territory to conduct anti-terrorist operations against extremists in Ingushetia," Kadyrov said, referring to a neighbouring region. "If you are the masters of your territory, then you need to watch over it."

Russia's interior ministry called the remarks "unacceptable", while a spokesman for President Vladimir Putin declined to respond directly to the Chechen leader's remarks.

"We have seen it. We have heard it. We have read it. I will not be making any comment," spokesman Dmitri Peskov was quoted as saying by RIA Novosti agency.

Kadyrov, 38, has ruled Chechnya with an iron fist since being installed by Putin in 2007, and has helped the Kremlin battle an Islamist insurgency in the North Caucasus.

But the former rebel -- accused by human rights groups of overseeing torture, extrajudicial executions and corruption -- has shown an increased readiness in recent months to challenge Putin's authority.

In one notable run-in in December, Putin criticised Kadyrov for saying that families of Islamist insurgents would be punished for a deadly rebel attack on the Chechen capital Grozny.

Putin at the time said Kadyrov had no right to make such declarations and said "everyone in Russia must observe the laws".