Ukraine’s president on Monday renewed his denial of a quid pro quo with Donald Trump over military aid, despite a growing case against the US president in impeachment proceedings in Washington.

“I did not speak with US President Trump in those terms: you give me this, I give you that,” Volodymyr Zelensky said in an interview with European publications including Germany’s Der Spiegel magazine.

In remarks published in German, Zelensky said he “did not understand at all” the accusations heard at the hearings and did not “want to give an impression that we are beggars” in Ukraine.

The scandal centers around a phone conversation on July 25 in which the Republican leader is suspected of putting pressure on Ukraine to launch investigations against former Democratic vice president Joe Biden and his son Hunter, who worked for a Ukrainian gas company.

The key issue is whether Trump set up a “quid pro quo” - Latin for seeking one action in exchange for another - with Zelensky by holding back promised US military aid for Ukraine until the Bidens were investigated.

In the interview published on Monday, Zelensky also played down expectations ahead of a summit on December 9 in Paris in which he is set to meet his Russian counterpart Vladimir Putin for the first time.

He said that an end to the conflict with Russia-backed separatists in eastern Ukraine could not be discussed until three preliminary steps had been taken.

He said there should first be a prisoner exchange within a “reasonable time period,” followed by a genuine ceasefire and the retreat of all armed forces to allow local elections to be held in the region.

“If these three issues are resolved, then we can see if everyone wants to put an end to the conflict.”

The conflict in Ukraine, which broke out in 2014 after pro-Western politicians took power in Kiev and Russia annexed Crimea, has killed more than 13,000 people.