Ukraine's President Volodymyr Zelenskiy demanded rapid changes in the operations of Ukraine's military medical system, as he announced the dismissal of the commander of the medical forces.

Zelenskiy's move was announced as he met Defence Minister Rustem Umerov, and coincided with debate over the conduct of the 20-month-old war against Russia, with questions over how quickly a counteroffensive in the east and south is proceeding.

"In today's meeting with Defence Minister Umerov, priorities were set," Zelenskiy said in his nightly video address. "There is little time left to wait for results. Quick action is needed for forthcoming changes."

Zelenskiy said he had replaced Major-General Tetiana Ostashchenko as commander of the Armed Forces Medical Forces.

"The task is clear, as has been repeatedly stressed in society, particularly among combat medics, we need a fundamentally new level of medical support for our soldiers," he said.

This, he said, included a range of issues -- better tourniquets, digitalisation and better communication.

Umerov acknowledged the change in a post on the Telegram messaging app, and laid out digitalisation, tactical medicine and rotation of servicemen as his top priorities.

"The experience of the effectiveness of specific units should be extended to the entire defense forces."

Ukraine's military reports on what it describes as advances in recapturing occupied areas in the east and south and last week acknowledged that troops had taken control of areas on the eastern bank of the Dnipro River in southern Kherson region.

Ukrainian commander in chief General Valery Zaluzhniy, in an essay published this month, said the war was entering a new stage of attrition and Ukraine needed more sophisticated technology to counter the Russian military.

While repeatedly saying advances will take time, Zelenskiy has denied the war is headed into a stalemate and has called on Kyiv's Western partners, mainly the United States, to maintain levels of military support.

Ostashchenko was replaced by Major-General Anatoliy Kazmirchuk, head of a military clinic in Kyiv.

Her dismissal came a week after a Ukrainian news outlet suggested her removal, as well as that of others, was imminent following consultations with paramedics and other officials responsible for providing support to the military.