Almost 1,000 mourners gathered in central Kyiv on Sunday for the memorial service of a high-profile journalist and volunteer combat medic who was killed in action last week.

Iryna Tsybukh, known as Cheka, was a 25-year-old paramedic who was on rotation in Ukraine's northeast region, where Russian forces launched a major ground offensive last month, capturing swathes of territory and forcing civilians to evacuate.

At her funeral service at the Saint Michael's Golden-Domed Monastery on Sunday, hundreds wore colourful Ukrainian vyshyvankas -- embroidered national shirts -- and carried Ukrainian flags and flowers.

Her coffin was also draped in the yellow-and-blue Ukrainian flag.

Part of the Hospitallers volunteer battalion, Tsybukh was credited with saving the lives of many soldiers, often risking her own life to evacuate injured servicemen from the front lines.

"She was one of those who not only defended the country, but also worked tirelessly to encourage others to join, train, and learn how to be effective," President Volodymyr Zelensky said last week.

Her volunteer battalion said her death was a "loss for all of Ukraine."

Last year while serving on the front lines in the eastern Donetsk region, she wrote a farewell letter to be published in the case of her death.

"I am not sorry to die, because I am finally living the life I would like. I will not lie, to feel this indispensable, true freedom, I will have to go through more than one more session of therapy, fears and tears," the letter, published by her brother, said.

She added: "Be worthy of the deeds of our heroes, don't be sad, be brave."