U.S. President George W. Bush on Saturday congratulated Kazakhstan's president, Nursultan Nazarbayev, on his re-election and urged him to investigate allegations of voting irregularities, according to Reuters. Nazarbayev told Bush that his government was prepared to investigate the charges, the White House said. Nazarbayev won re-election by a landslide on Monday in the central Asian state, but international observers branded the vote flawed. Blair Jones, a White House spokesman, said Bush called Nazarbayev to "congratulate him on his re-election and to highlight the importance of continued democratic reform in Kazakhstan." "Allegations of irregularities in the election were noted and the (U.S.) president stressed the importance of Kazakhstan investigating the facts related to these allegations," Jones said. "Nazarbayev said Kazakhstan is prepared to investigate the facts provided to them."