Former Ukrainian President Viktor Yanukovych's request to Russian President Vladimir Putin to use the Russian Armed Forces on the territory of Ukraine dated March 1, 2014 was necessary for the Russia to justify its aggression in Crimea, former permanent representative of Ukraine to the United Nations UN Yuriy Serheyev has said.

"The Russian Federation needed this appeal to justify its intervention. This appeal complicated our work in the line of defense of Ukraine's interests," he said appearing on Tuesday as a witness at a sitting of Kyiv's Obolonsky District Court in the treason case against Yanukovych.

Serheyev noted it was Russia that initiated a meeting of the UN Security Council on March 3, 2014, where this letter was read out by Viktor Yanukovych. He believes that this appeal was necessary for the Russian side to confirm its line that there was a coup d'état in Ukraine that threatened Russians and the Russian-speaking population of Crimea, as well as the Russian Black Sea Fleet base on the peninsula.

According to the former permanent representative of Ukraine in the United Nations, Yanukovych's appeal to Putin worked to disorient the public "about who is who and what happened, giving a kind of legitimacy to those actions."

Answering a question of the defense counsel of the ex-president on whether Yanukovych's appeal to Putin had legal significance for Ukraine, Serheyev said: "It terms of harm it did, this later resulted in concrete actions, it legitimized the actions of the Russian Federation... Though they were unlawful by nature, it was used to justify these actions within the UN."