President of Kazakhstan Kassym-Jomart Tokayev has told Russian President Vladimir Putin that "what is happening now is an internal problem of Russia," The Guardian reports.

A statement posted on Tokayev’s official website said: “Head of State Kassym-Jomart Tokayev spoke by phone with Russian president Vladimir Putin. Vladimir Putin gave information about the situation in the country.

“Kassym-Jomart Tokayev noted that what is happening now is an internal problem of Russia. Constitutional order and the rule of law are the main conditions for maintaining the legal order in the country. This is the basis of society’s security and its successful development.

“Vladimir Putin thanked Kazakhstan for understanding the current situation in the Russian Federation.”

Russian military helicopters opened fire on Saturday afternoon on a convoy of rebel mercenaries already more than half way towards Moscow in a lightning advance after seizing a southern city overnight.

President Vladimir Putin vowed to crush an armed mutiny he compared to Russia's Civil War a century ago, Reuters reports.

Fighters from Yevgeny Prigozhin's private Wagner militia were in control of Rostov-on-Don, a city of more than a million people close to the border with Ukraine, and were rapidly advancing northwards through western Russia.