MOSCOW: The rebel Wagner mercenary force threatened to march on Moscow on Saturday before announcing a stunning pullback, as Kyiv seized on the chaos to launch new assaults against Russian positions in Ukraine.

Before Wagner chief Yevgeny Prigozhin`s apparent climbdown, Russian regular forces had launched what one regional governor called a `counter-terrorist operation` to halt the Wagner advance northwards up a main highway towards Moscow.

The private army captured a key military headquarters in southern Russia, and sent a force north to threaten the capital, defying Vladimir Putin`s warning of civil war.

In the capital, the mayor urged Muscovites to stay indoors and declared Monday a day off work.

Prigozhin said his troops had taken control of the military command centre and airbase in the southern city of Rostov-on-Don, the nerve centre of Russia`s offensive in Ukraine.

`We got to Rostov. Without a single shot we captured the HQ building, he said, claiming that local civilians had welcomed the operation and vowing to overthrow Russia`s military command.

Responding to the challenge in a televised address, Putin accused Prigozhin-whose private army provided shock troops for Moscow`soffensive in Ukraine of a `stab in the back` that posed a threat to Russia`s very survival.

Kyiv revelled in the chaos, as Putin`s former mercenary ally turned his Wagner force away from the offensive against Ukraine and made to topple the chiefs of Russia`s military.

But amid Russia`s most serious security crisis in decades, Prigozhin delivered a surprise announcement, saying his troops were turning backto avoid bloodshed in the Russian capital.

Belarusian leader Alexander Lukashenko said he had negotiated a truce with Prigozhin `on stopping the movement of armed individuals from the Wagner group on Russian territory andfurther steps on deescalating tensions.

`We are turning our columns around and going back to field camps,` Prigozhin announced.

Hours later, the Kremlin said Prigozhin would leave for Belarus and a criminal case against him would be dropped. Those who had joined the `armed rebellion` would not be prosecuted, Kremlin spokesman Dmitry Peskov added.-AFP