REUTERS

Mr  Groysman published a list of his assets in line with Ukraine's new anti-corruption rules, which compel all senior public officials to declare their wealth in a new electronic database, according to the BBC.

He has been a public official in Ukraine for the past 14 years.

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Reforms are required for Kyiv to continue enjoying Western support.

Around 50,000 top public officials, including judges, politicians and civil servants, are expected to publish their declarations by Sunday.

In a statement published on his Facebook page, Mr Groysman said his "considerable savings" were down to "property and my corporate rights…along with income from my wife's business."

He is not the only Ukrainian politician to possess an eye-watering amount of cash.

Another member of parliament, Viktor Romanyuk, has declared that he has $753,000 (£618,000).

And the controversial mayor of Ukraine's second biggest city Kharkiv, Gennadiy Kernes, has declared that he has more than $1.6 million in hard currency.

The habit of some senior politicians to hoard cash is hardly a vote of confidence in the country's banks, which themselves have been undergoing extensive reforms.

"A person who has cash doesn't trust the financial system," said Alexander Valchyshen, from Kyiv-based asset management group ICU.

"True accounting", he said, was needed to create a stable economy and to stop "financial cheating" and increase confidence in the banks.

However, overall Ukraine's e-declaration scheme is seen as a crucial step in tackling corruption, which is a key concern for foreign investors.

Oleksandra Ustinova from Ukraine's Anti-Corruption Action Centre described the new scheme as "revolutionary".

She hopes the system, which will automatically flag up suspect declarations for the new anti-corruption bureau to investigate, will lead to prosecutions.

Ms Ustinova said 500 judges had already resigned, instead of completing their declarations.

Read alsoE-declaration system DDoS-ed - Special Communication ServiceAnd she believes a new anti-corruption court is key if Ukraine is to capitalize on the new reforms and start prosecuting corrupt officials.

Draft legislation for the creation of such a court is expected to come before Ukraine's parliament in the coming weeks.

There is no evidence that any of the politicians mentioned in this article have broken the law.

And the online declarations are likely to please Ukraine's backers in Washington and Western Europe.

Read alsoWhen will Ukrainians get European salariesThe UK Ambassador to Kyiv, Judith Gough, tweeted that the prime minister's declaration was an "important step".

Ukraine's President Petro Poroshenko, one of the richest men in the country, is still to complete his declaration.

A spokesman said it would be finished before Sunday's deadline.

Before becoming president Mr Poroshenko amassed considerable wealth running a chocolate business.