Russian Deputy Finance Minister Anton Siluanov has been appointed to replace Finance Minister Alexei Kudrin, who says the country is facing increased budget risks.

Kudrin made his comments in a statement Tuesday, a day after he resigned following a public disagreement with Russian President Dmitry Medvedev. The long-serving finance minister criticized the government for the increased fiscal risks it was taking, making clear there had been disagreements on budget policies for months. He said Prime Minister Vladimir Putin had rejected an initial request he made in February to resign.

Mr. Putin earlier Tuesday named Siluanov as acting finance minister. Mr. Putin also said Deputy Prime Minister Igor Shuvalov would expand his duties to include the economy.

The Standard and Poor's ratings agency said Tuesday that Kudrin's departure would not have an immediate impact on Russia's sovereign credit ratings. The agency said it did not expect any significant change in the country's economic and fiscal policies, or the close link between politics and business.

But it added that changes in political roles and personnel could make it more difficult for Russia to strengthen the country's long-term growth potential.

Kudrin quit Monday after saying he would not support President Dmitry Medvedev if he were to become the country's new prime minister.

On Saturday, Mr. Putin confirmed his intentions to run for the presidency in national elections in March 2012. He is widely expected to win and has said he would propose that Mr. Medvedev become prime minister.

Kudrin had been Russia's finance minister since 2000. He was seen as an effective fiscal conservative and widely credited with helping Russia get through the 2008 global financial crisis.