U.S. President Donald Trump proposed a White House summit when he called Russian President Vladimir Putin last month, prior to the mass expulsion of Russian diplomats from the U.S., a top Kremlin aide said Monday.

"Trump proposed holding a meeting at the White House in Washington," Putin's top foreign policy aide, Yury Ushakov, told reporters.

The Kremlin said on Monday no planning discussions had been held on a proposed summit Putin and Trump since the U.S. leader proposed the meeting in a phone call on March 20.

Since then, Washington expelled 60 Russian diplomats and closed the Russian consulate in Seattle over allegations of a Russian role in the poisoning of former Russian spy Sergei Skripal and his daughter. Russia retaliated in kind, expelling 60 American diplomats and closing the U.S. consulate in St. Petersburg.

"Against the backdrop of these events, it's difficult to discuss the possibility of holding a summit", Kremlin aide Yuri Ushakov told a news briefing.

"We want to believe that the discussions (on a proposed summit) will begin," Ushakov said. "We want to hope that... one day, at one time or another we can arrive at the start of a serious and constructive dialogue."