A diplomatic source told the PA news agency Mr Prystaiko had been fired after publicly criticising Mr Zelenskyy.
Speaking to Sky News’ Kay Burley last week, he labelled the president’s “sarcastic” response to demands he shows more gratitude for Western support as unhealthy.
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As well as being sacked as UK ambassador, Mr Prystaiko has been removed as Ukraine’s representative to the International Maritime Organization.
Before being appointed to London in July 2020, he spent two decades working in Kyiv’s foreign policy unit.
He has worked in embassies and consulates around the world, including in Australia, Canada, and the US, and was Ukraine’s head of mission for NATO in 2017.
Mr Prystaiko has also served as his president’s foreign policy adviser and deputy chief of staff.