Russian Deputy Finance Minister Anton Siluanov has been appointed to replace Finance Minister Alexei Kudrin, who resigned after a public disagreement with the Russian president.

Prime Minister Vladimir Putin on 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 Kudrin’s departure would not have any 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.

Mr. Medvedev over the weekend announced that Mr. Putin would run for the presidency in national elections in March 2012. Mr. Putin is widely expected to win. He said he would propose that Mr. Medvedev become prime minister in a new Putin presidency.

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.