The United States on Tuesday urged Ukraine to pick a credible top prosecutor to replace one sacked by President Volodymyr Zelensky, calling for action on corruption even as Kyiv battles Russian invaders.

"We join the people of Ukraine in emphasizing the importance of transparently appointing a highly qualified and truly independent successor as prosecutor general," State Department spokesman Ned Price told reporters.

"The independence and impartiality of the prosecutor general is vital to ensuring the integrity of accountability efforts in Ukraine," he said.

Price said that the fight against corruption, long a major concern in Ukraine, was critical as the country seeks membership in the European Union.

"Corruption must be combated even as Ukraine defends itself against Russia's war of aggression. Russia's war against Ukraine poses an external threat. Corruption poses an internal threat," he said.

Ukraine's Prosecutor General Iryna Venediktova, who was recently sacked, meets French President Emmanuel Macron at the French embassy in Kyiv in June 2022
Ukraine's Prosecutor General Iryna Venediktova, who was recently sacked, meets French President Emmanuel Macron at the French embassy in Kyiv in June 2022 POOL via AFP / Ludovic MARIN

Zelensky announced earlier this month that he was firing prosecutor general Iryna Venediktova as well as security chief Ivan Bakanov.

Zelensky cited the need to act against suspected treason by officials supporting Russia. The president had been critical of the two senior figures' performance even before Russia's invasion on February 24.

The United States, which has poured billions of dollars into Ukraine to help it repel Russia, has a memorable history of addressing corruption in Ukraine.

President Joe Biden, while serving as vice president, demanded on a trip to Kyiv that Ukraine fire an earlier prosecutor general seen as ineffective in fighting corruption, warning that the United States would otherwise withhold $1 billion in loan guarantees.

The episode became the source of unfounded conspiracy theories by former president Donald Trump, who was impeached for withholding security aid to Ukraine unless Zelensky agreed to dig up dirt on Biden.