Deep strains emerged Thursday in the ranks of Ukraine's pro-Moscow insurgents as dozens turned in their weapons in disgust at Russian inaction and bickering broke out between rebel factions.

In the past two weeks, Ukrainian government troops have halved the amount of territory held by the rebels and have grown better equipped and more confident by the day. Once fearful of losing further pieces of Ukraine to Russia, they have shifted their strategy to containing the insurgents, whose pleas to join Russia have been ignored by President Vladimir Putin.

Pushed back into Ukraine's eastern industrial city of Donetsk, the pro-Russia militias appear to be focusing their efforts now on hit-and-run operations, bombing transportation links and bracing for more assaults from government forces.

'Russia abandoned us. The leadership is bickering. They promise us money but don't pay it. What's the point of fighting?'- Oleg, Ukrainian miner turned pro-Russian rebel

Signs of a rift within the rebellion became evident Thursday when the head of the influential Vostok battalion announced he would not submit to the authority of the military leader of the separatist Donetsk People's Republic, Igor Girkin.

Girkin, a Russian better known by his assumed name Strelkov, has attained hero status among supporters of the insurgency. Ukrainian authorities have identified him as a former Russian military intelligence agent active in taking over Crimea before Russia annexed it in March.

Yet he has also been criticized by some for leading the rebel withdrawal last weekend from the eastern city of Slovyansk, 110 kilometres north of Donetsk, reportedly to protect civilian lives.

Vostok commander Alexander Khodakovsky alluded to that.

"There cannot be a single leader giving orders," he declared. "Because if Strelkov suddenly decides what he wants is -- in the interests of protecting the lives of Donetsk citizens and the lives of militiamen -- to abandon Donetsk, then we will not follow his orders." 

Khodakovsky was speaking in Makiivka, a town just outside Donetsk, where his men relocated after a reported falling-out with Strelkov.

The ill will also appears to stem from a feeling among the rebels that Russia has done too little to help them.

"Strelkov is a military officer of non-local domicile, while we are locals and will not, therefore, allow the people of Donetsk to remain without our support and protection," Khodakovsky said.

Strelkov could go back to Russia whenever he wanted, he noted.

Kyiv, rebels at ceasefire impasse

The Ukrainian government in Kyiv has accused Moscow of arming and supporting the rebels, charges it has denied.

Also on Thursday, Ukrainian President Petro Poroshenko told U.S. Vice President Joe Biden that Russia and Ukrainian separatists had refused multiple proposals by Kyiv for venues to negotiate a ceasefire.

"The Vice President told President Poroshenko that the United States was discussing with its partners in the international community the need to hold Russia accountable for its continued support for the separatists," White House officials said.

The U.S. and other Western countries have repeatedly threatened to add more economic sanctions against Russia if it doesn’t de-escalate the situation with Ukraine.

‘Russia abandoned us’

In another sign of deteriorating morale among the rebels, several dozen militia fighters garrisoned in a university dorm in Donetsk abandoned their weapons and fatigues in their rooms Thursday.

UKRAINE-CRISIS

Ukrainian forces recaptured the key city of Slovyansk earlier this week, but the pro-Russian militants have dug in to fortified positions and are vowing to continue fighting. (Gleb Garanich/Reuters)

"Russia abandoned us. The leadership is bickering. They promise us money but don't pay it. What's the point of fighting?" said 29-year old Oleg, a former miner.

Oleg, who declined to give his surname for fear of being punished for desertion, said he had served in the militia for a month and planned to go home to Makiivka.

Strelkov has admitted substantial difficulties enlisting the support of the locals in eastern Ukraine.

"In truth, the number of volunteers for the several million-strong population of Donbass, for a mining region where people are used to dangerous and difficult work, has been somewhat low," he told a rebel-run TV station this week. "It is very difficult to protect this territory with the forces at our disposal."

At a news conference, the prime minister of the Donetsk People's Republic dismissed talk of infighting.

"These are lies and disinformation. There are no disagreements. We are now organizing our joint work," Alexander Boroday said.

With files from Reuters