By Andrew Osborn

MOSCOW (Reuters) -Russia has removed Sergei Surovikin, nicknamed "General Armageddon", as head of the air force after he vanished from public view during a Wagner mercenary mutiny against the top army brass, two Russian news outlets reported on Wednesday.

A recipient of Russia's top military award, Surovikin is the most senior Russian military figure to lose his job over the June 23-34 mutiny, which President Vladimir Putin said could have tipped Russia into civil war.

Wagner boss Yevgeny Prigozhin, who spearheaded the revolt, remains free and on Monday posted a video address which he suggested was shot in Africa. The two men Prigozhin had wanted to topple - Defence Minister Sergei Shoigu and Valery Gerasimov, chief of general staff - remain in their posts.

Once commander of Russia's overall war effort in Ukraine when he was lauded by Russian and Western military experts as one of its most effective operators, Surovikin has not yet been publicly fired.

However, Russian state news agency RIA cited an unnamed but "informed" source as saying: "Ex-chief of the Russian Air and Space Forces Sergei Surovikin has now been relieved of his post, while Colonel-General Viktor Afzalov, head of the main staff of the Air Force, is temporarily acting as commander-in-chief of the Air Force".

The RBC news outlet - citing two unnamed sources familiar with the situation - also reported that Surovikin had been removed from his post.

It cited them as saying he was being reassigned to a different job, was currently on leave, and had also lost his role as deputy commander of Russia's forces in Ukraine.

Reuters could not independently verify the reports and there was no immediate official confirmation.

Surovikin's reported removal and the appointment of an acting successor suggests the authorities found fault with his behaviour during the revolt, and appears to be part of a drive to remove or sideline anyone deemed too close to Wagner.

Since the mutiny, the authorities have also moved to silence prominent critics of the way Russia is prosecuting the war - both inside the army, as in the case of one Russian general, and from the sidelines, in the case of nationalist Igor Girkin.

'GENERAL ARMAGEDDON'

U.S. officials told Reuters in June that Surovikin had been supportive of Prigozhin, but that Western intelligence did not know with certainty whether he had helped the rebellion in any way.

Given Surovikin's reputed competence, some Western military experts have suggested his removal from battlefield operations could hurt Russia's campaign in Ukraine, something it calls "a special military operation".

Surovikin's last public appearance was on June 24, the second and final day of the mutiny, when he appeared in what looked like a carefully stage-managed video. Visibly strained, without insignia and cradling an automatic weapon, he urged Prigozhin to abandon his march on Moscow.

Since the mutiny, which was ended by negotiations and a Kremlin deal, some Russian news outlets and sources have said that Surovikin, who was often publicly praised by Prigozhin in the run-up to the revolt, was being investigated for possible complicity in it and being held under house arrest.

Surovikin earned the nickname "General Armageddon" during Russia's military intervention in Syria for the ruthless bombing tactics he employed there.

He was placed in charge of Russian military operations in Ukraine last October, but in January that role was handed to General Valery Gerasimov, chief of general staff, and Surovikin was made a deputy to Gerasimov.

Afzalov was previously deputy to Surovikin and has been chief of staff of the Aerospace Forces for at least four years, according to British military intelligence. Ukraine says he played a direct role in the planning and prosecution of Russia's onslaught against it.

During Surovikin's absence from public view, Afzalov was shown on television briefing Gerasimov last month.

(Reporting by Andrew Osborn; Editing by Mark Trevelyan and Bernadette Baum)