The military leader of pro-Russian rebels in the eastern Ukrainian city of Donetsk, Igor Girkin - known as Strelkov - has resigned.

Alexander Borodai, the former PM of the self-declared Donetsk People's Republic, confirmed the news but denied reports Mr Strelkov had been wounded.

There has been heavy shelling both in Donetsk and Luhansk as Ukrainian forces battle the separatists.

The news came with a disputed Russian aid convoy stationed near the border.

Mr Borodai confirmed Strelkov's departure to Russian media but gave no reason.

He said reports that Strelkov, a Russian citizen, had been injured were "total rubbish".

"You probably already know that he, like myself, has left his post," Mr Borodai said in a video posted by Russia's pro-Kremlin Life News website.

"The [Donetsk People's Republic] already has a new defence minister."

Mr Borodai said the new minister went by the nom de guerre Tsar. His name was given by other sources as Vladimir Kononov.

There have been two other high-profile resignations of rebel leaders in the past week.

Mr Borodai handed over to Alexander Zakharchenko as "prime minister" in Donetsk and the rebel chief in Luhansk, Valery Bolotov, said he was temporarily handing over to his defence minister, Igor Plotnitskiy.

The Russian aid convoy of at least 260 lorries, which moved towards the border on Thursday, has now halted.

There is continuing confusion over the final destination. This afternoon, the lorries were parked in a field.