German Chancellor Olaf Scholz’ emails were reportedly seized by investigators in the probe into the “Cum-Ex” tax fraud scheme which siphoned off billions of euros from central banks across Europe.

According to a report on Monday from the Hamburger Abendblatt newspaper, Olaf Scholz’ official email address from when he served as mayor of Hamburg — olaf.scholz@sk.hamburg.de — was taken by investigators in March.

The investigation is centred around the “Cum-Ex” — Latin for with-without — tax fraud scheme, described as “the biggest tax theft in the history of Europe”. The scheme saw traders and banks exploit the time lag between when a trade was executed and when it was actually settled, enabling some to claim more than one tax refund from the government as it was unclear who exactly owned the share during the interval between the sale and payment.

This meant that each side of the transaction could claim a tax rebate from the government on the same money. The fraud scheme was so successful that it is believed to have tricked treasuries across Europe into paying out over 55 billion euros in taxpayer cash.

Germany was particularly hard hit by the scheme, with an estimated €31.8 billion lost between 2001 and 2016, according to calculations from tax expert Christoph Spengel of the University of Mannheim.

The probe, which has seen dozens arrested in Germany, has now entered around whether politicians had any involvement in the use of cum-ex transactions with the Warburg Bank in November of 2016 when 47 million euros that were pilfered through fraud were written off by the government.

German Chancellor Olaf Scholz, who was serving as mayor of Hamburg during the time in question, has denied any wrongdoing. However, he has claimed that his memory lapsed in regard to holding meetings with a Warburg Bank shareholder.

The leftist leader of the traffic light coalition government in the German parliament will have to face grilling at the Parliamentary Committee of Inquiry in Hamburg later this month in connection to the scandal.

The search of Scholz’ email is allegedly in connection to a the investigation against fellow Social Democrat Party (SPD) politician Johannes Kahrs, who previously served as the head of the tax administration department responsible for overseeing the Warburg Bank.

Kahrs has been accused of receiving favours for helping with tax evasion. According to a report from the Bild tabloid, investigators found over 200,000 euros in cash in a bank safe under his name without any clear origin.

Government spokesman Steffen Hebestreit has said that he was unaware of the claims from Hamburger Abendblatt that Scholz’ emails were investigated, but added that “there is also nothing to hide”.

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