Irish Prime Minister Bertie Ahern has sent his "warmest congratulations" to US President George W. Bush who has won a second term as US president on Wednesday.

It was important to maintain a strong transatlantic relationship and to work together across the range of issues that face the international community at this time, Ahern was quoted as saying in a statement after Bush's Democratic challenger John Kerry has admitted defeat to Bush.

"The contribution which people of Irish heritage have made to the United States, and the strong tradition of friendship and goodwill between us, is a source of enormous pride to us," Ahern said.

"Today, as our connections and links continue to expand in a broad range of areas of mutual interest, I look forward to working with the president to ensure that these continue to develop and flourish in the years ahead," he added.