The British government has distanced the incoming head of its foreign intelligence service from her grandfather following reports he was a Nazi spy known as “the Butcher”.

Blaise Metreweli will, in the autumn, become the first woman to lead MI6 in its 116-year-old history, the British government announced earlier this month.

The Daily Mail newspaper reported this week that her grandfather Constantine Dobrowolski defected from the Soviet Union’s Red Army to become a Nazi informant in the Chernigiv region of modern-day Ukraine.

The newspaper said German archives showed Dobrowolski was known as “the Butcher” or “Agent No 30” by Wehrmacht commanders.

“Blaise Metreweli neither knew nor met her paternal grandfather,” a Foreign Office spokesperson said in a statement.

“Blaise’s ancestry is characterised by conflict and division and, as is the case for many with eastern European heritage, only partially understood. It is precisely this complex heritage which has contributed to her commitment to prevent conflict and protect the British public from modern threats from today’s hostile states, as the next chief of MI6.”

The Daily Mail said Dobrowolski had a 50,000 ruble bounty placed on him by Soviet leaders, and was dubbed the “worst enemy of the Ukrainian people”.

He also sent letters to superiors saying he “personally” took part in “the extermination of the Jews”, the newspaper added.

The head of MI6 is the only publicly named member of the organisation and reports directly to the foreign minister.

Metreweli, 47, will be the 18th head of MI6.

Like her predecessors, she will be referred to as “C”, not “M” as the chief is called in the James Bond film franchise.