Former Russian separatist leader Igor 'Strelkov' Girkin has finally admitted in an interview with a state-run news agency that he is a colonel for the FSB security services.

Strelkov, who declared himself minister of defence of the self-proclaimed Donetsk People's Republic, was long rumoured to be a covert agent of Russia's GRU military intelligence in the past. A veteran of both the Soviet and Russian armies, he was charged by Ukraine authorities with terrorism for acts during the current conflict in Eastern Ukraine.

In the interview with Kremlin-funded Rossiya Segodnya agency, which incorporates the former RIA Novosti and Voice of Russia, Strelkov responds to critics who question his experience in planning military operations by saying:

"I really am a FSB colonel, so I have a calm attitude and I do not advise you to call my military rank lower than it is. The title has a higher value for the military than [it has] for civilians."

The agency later redacted the interview, removing the passage mentioning the FSB, but the original version can still be seen on PolitNavigator website. The author Alexander Chalenko explained the changes by saying that the editor wanted to reduce the article's length and keep "the right questions and answers".

Other parts of the interview that were removed by the news agency relate to the recent offensive by pro-Russian rebels backed by Russian special forces on Donetsk airport. Strelkov argued that the attack at the airport "is not only unnecessary, it is also harmful" causing serious losses to his previous unit.

The shadowy commander also recounted how Russian military units fighting in Eastern Ukraine were in disarray, not interacting with each other - but also this bit was lifted by Rossiya Segodnya.

Earlier in November, Strelkov released another interview in which he took responsibility for triggering war in Eastern Ukraine.

"If our unit had not crossed the border, everything would've come to an end, like in Kharkiv [Ukrainian city], like in Odessa," he said, in a translation by the Moscow Times.

"There would have been several dozen killed, burned, detained. And that would have been the end of it. But the flywheel of the war, which is continuing to this day, was spun by our unit. We mixed up all the cards on the table."

Called "one of the most powerful separatist figures in eastern Ukraine," Strelkov is a suspect in the downing of the Malaysian Airlines MH17. He resigned from his post earlier in August.

An IBTimes UK investigation showed that the charismatic Russian separatist leader was involved in the bloody Bosnian war of the early 1990s.

Ukraine and Russian-backed rebels have agreed to a fresh ceasefire in Luhansk, one of the two provinces controlled by separatists.

The Organisation for Security and Cooperation in Europe (OCSE) special monitoring mission in Ukraine published news of the deal, adding that the withdrawal of heavy weapons would start on 6 December.

It is isn't the first time that a ceasefire has been declared in the region. Ukraine and rebel forces signed a deal on 5 September to stop hostilities, but fighting continued.

Nato secretary general Jens Stoltenberg blamed the separatists for their failure to honour the deal. "The government in Ukraine has really made strong efforts to implement the different provisions within the Minsk agreements."

"The problem has been that the separatists and Russia are not respecting the Minsk agreements," he said, according to Interfax-Ukraine news agency.