Former President Donald Trump has defended his special envoy Steve Witkoff as doing the standard thing after a leaked recording appeared to show him advising a Russian official on how to appeal to the US president.

Trump told reporters on Wednesday that he had not heard the audio but that Witkoff was doing what a dealmaker does to sell a US-authored peace plan to both Russia and Ukraine.

The leaked call from last month emerged days after the 28-point draft peace plan was presented by the US, which largely reflected Russian positions on ending its full-scale war in Ukraine.

Witkoff has visited Moscow several times this year and will meet Russian President Vladimir Putin again next week.

He has never traveled to Kyiv in his role as special envoy, though other US officials have visited, and US Army Secretary Dan Driscoll went to Kyiv this week. Trump says he will hold further talks with the Ukrainians.

Diplomatic efforts have continued after the initial draft plan faced criticism from Ukrainian and European leaders as being overly favorable to Russia, which included proposals concerning territory in eastern Ukraine controlled by Kyiv.

The plan has since been revised to better reflect Ukraine's interests and the perspectives of European allies. Ukrainian President Volodymyr Zelensky has expressed his willingness to meet with Trump to discuss outstanding sensitive points.

In the leaked audio recording obtained by Bloomberg, Witkoff appeared to coach Yuri Ushakov, Putin's foreign policy adviser, on how to positively engage with Trump. Witkoff emphasized the importance of acknowledging Trump's achievements and promoted the idea of a peace deal.

As the diplomatic landscape evolves, Trump remains optimistic about the prospects for peace negotiations and maintains that Witkoff's approach is part of effective diplomacy.