South African police confirmed on Monday they were looking into publicly-funded renovations worth $23 million (18 million euros) at the president's rural homestead in the eastern province of KwaZulu-Natal.

Zuma has maintained that the refurbishments at the Nkandla property, which include a swimming pool, private clinic and amphitheater, were for security purposes.

"The investigation in this regard has been initiated and no further information can be disclosed at this juncture as the matter is still sub judice…suffice to say that all processes have been followed," Police Minister Nathi Nhleko said in a written statement to parliament.

Zuma's office has not issued a comment on the investigation.

Zuma is serving his second term as president after winning general elections in May, and has been heavily criticized for excessive spending in a country grappling with poverty, unemployment and deep inequality. He has faced repeated calls from opposition politicians to step down.

The police investigation comes in response to corruption charges filed against Zuma by Democratic Alliance opposition leader Mmusi Maimane in March.

At the time, Maimane said: "There can be no doubt that this Nkandla palace was built on corruption by the president for the president with our money."

Earlier this year the South African ombudsman released a highly critical report on Zuma's home, saying the president should pay part of the costs, and that he had "benefited unduly" from it.

It's not the first time Zuma is being investigated for mishandling money. In 2009, dozens of corruption charges against Zuma relating to a multi-billion dollar arms deal were dropped.

South Africa is ranked 72 out of 177 on the corruption index of the non-profit organization Transparency International.

nm/tj (AFP, epd)