KIEV (Reuters) - Ukrainian authorities will investigate politicians and officials who declare cash assets of more than $100,000 and will impose prison sentences of up to 15 years on any found guilty of wrongdoing, General Prosecutor Yuriy Lutsenko said on Tuesday.

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His announcement came after Ukraine completed a landmark anti-corruption reform on Sunday obliging tens of thousands of officials, all the way up to the president and prime minister, to declare their wealth in an online database.

Although a Western-backed government came to power in 2014 promising reform, corruption remains entrenched. Declarations of millions of dollars in cash, expensive Swiss watches and luxury cars have shocked many in a country where the average monthly salary is little over $200.

“The online declaration is not the end of the process, but only the beginning,” Lutsenko told a briefing, adding more than half of the lawmakers in parliament had declared possession of more than $100,000 in cash.

The reform, which is backed by the EU and the International Monetary Fund, faced what some lawmakers and activists said were repeated attempts to sabotage it or water it down.

“The important stage of verification of submitted e-declarations now starts,” Thomas Frellesen, the charge d’affaires of the EU delegation to Ukraine, told Reuters by email. The investigating body “must be able to operate fully independent, free of any political interference,” he said.

Lutsenko said the authorities will also look into the tax affairs of those who reported receiving gifts of over $10,000 or said they had over $100,000 in the bank.

The prosecutor’s own family may not be immune from investigation. His wife, herself a lawmaker, declared owning $280,000 and 50,000 euros ($55,120) in cash, as well as a smaller amount in the local hryvnia currency.

The declaration system - whose launch was a key condition for further loans from Western backers - is designed to move away from a culture that tacitly allowed bureaucrats to amass wealth through cronyism and graft.

Khatia Dekanoidze, the chief of Ukraine’s under-resourced police force, said: “Frankly, if the police had 5 percent of what was declared, we’d be able to get new uniforms for everyone ... and have all our officers working in state-of-the-art buildings.”

On Monday, European Council President Donald Tusk said he had spoken to President Petro Poroshenko to congratulate him on efforts to fight corruption.

The anti-corruption agency NAZK has said it will verify the declarations, but with over 100,000 forms submitted, it is unclear how thorough the process can be.