Ukrainian President Volodymyr Zelensky's aide Andriy Yermak has said the handing over to Russia of Volodymyr Tsemakh, a person of interest in connection with the MH17 downing probe, will not affect Ukraine's relations with the EU.

In an interview with the Ukrayinska Pravda online newspaper, he said all the information that Tsemakh is a very important witness comes from the media.

"Whether he is an important witness or not – it is for the court to tell. Then we will understand if he's important," he said.

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"And as for certain political implications... The position of our partners is based not only on this case. There is a set of arguments on which the decision on sanctions rests. I don't think the release of Tsemakh will cause a review of our relations with partners," Yermak said.

He also confirmed the words of Ukrainian President Volodymyr Zelensky that all investigative actions as regards Mr Tsemakh had been carried out. If the Netherlands needs Tsemakh for the investigation, Yermak notes they have international legal mechanisms in place to coordinate this issue with Russia.