Russia is involved with the proposal for settling issues involving Crimea and Donbas that Verkhovna Rada Radical Party faction deputy Andriy Artemenko sent to the U.S. presidential administration, Ukrainian President Petro Poroshenko's representative to the Rada Artur Herasymov said on Monday.

Speaking if there was any politician behind Artemenko's proposal, Herasymov said the following: "I don't know about it. But we believe Russians are behind such plans 100 percent."

He added that the presidential administration was unaware of the plan.

"They did not gather these lands and they cannot give these lands away. Any horse-trading involving the return of these lands is impermissible," Herasymov said, adding that Artemenko should answer questions from his colleagues in parliament on Tuesday about his proposal to the Donald Trump administration.

Rada deputy Serhiy Leshchenko from the Poroshenko Bloc parliamentary faction, in turn, gave his version of Artemenko's plan.

"Everyone is discussing Artemenko's proposal. According to my information, the so-called 'Artemenko plan' was devised by Lyovochkin-Boyko/Surkov. Boyko was in Moscow for meetings not long ago. Artemenko's role was to deliver the plan and to act as a frontman in the future," Leshchenko wrote on his Facebook page.

Serhiy Lyovochkin and Yuriy Boyko are members of the Opposition Bloc faction in Ukraine's parliament. Boyko heads the faction.

Vladislav Surkov is Russian President Vladimir Putin's personal adviser.