By Dan Peleschuk

KYIV (Reuters) - Ukraine's government on Tuesday sacked a deputy defence minister in charge of weapons purchases amid infighting over procurement that is complicating Kyiv's attempt to reassure key Western partners at a critical moment in the war with Russia.

The dispute burst into the open last week after Defence Minister Rustem Umerov criticised Ukraine's arms procurement effort as having failed to deliver results for frontline troops.

Ukraine has sought to clean up defence spending as the war grinds towards its fourth year, an effort that has taken on greater importance as U.S. President Donald Trump considers whether to continue supporting Kyiv's military.

As well as requesting Dmytro Klimenkov's removal, Umerov leveled particular criticism at the Defence Procurement Agency, which coordinates weapons purchases for Ukraine's outgunned military.

The agency was established after a series of allegations earlier in the war of ministry misspending, and has aimed to cut out intermediaries and minimise the risk of corruption.

In a statement on Friday, Umerov said it had "inexplicably transformed into an 'Amazon'" and its purchases were too publicly visible. Ukraine has long sought to keep details of arms procurement a closely guarded secret.

Umerov also said that he would not renew a contract with agency chief Maryna Bezrukova, a reformer whose appointment last year had been applauded by Kyiv's Western partners. He pledged to install a new director.

The agency said in response that it had made "significant progress" in boosting supply and lowering prices, and that it would continue working under Bezrukova.

The standoff comes as Ukrainian troops face Russian advances across swathes of the east. Both sides are attempting to gain a battlefield edge ahead of any potential peace talks, but Kyiv's defences are buckling amid a shortage of men and weapons.

President Volodymyr Zelenskiy has urged Western partners to keep arms flowing to Ukraine. The defence ministry's own anti-corruption council, comprised of elected civic activists, said the infighting could compromise that effort.

"We believe the current situation is harmful to Ukraine, the Ukrainian military and our international relations," it said on Saturday. "We must be clear and predictable for partners."

In a statement on Monday, G7 diplomats in Ukraine urged officials to quickly resolve the dispute.

"Consistency with good governance principles and NATO recommendations is important to maintain the trust of public and international partners," they wrote.

(Reporting by Dan Peleschuk; Editing by Ros Russell)