WASHINGTON - The White House on Saturday lauded the second round of voting in Afghan presidential election, pledging to work with the new government.

"The United States congratulates the people of Afghanistan on the completion today of the second round of voting in their historic presidential elections," spokesman Jay Carney said in a statement, calling the polls "a significant step" forward on Afghanistan's democratic path.

"We look forward to working with the next government chosen by the Afghan people," he added.

Washington said the two candidates in the run-off race, namely former foreign minister Abdullah Abdullah and former World Bank economist Ashraf Ghani Ahmadzai, had indicated their readiness to sign a bilateral security agreement with the United States that grants legal immunity to remaining American troops.

Hamid Karzai, the incumbent Afghan president, has refused to sign the deal despite the Obama administration's pressure.

President Barack Obama announced in late May that U.S. and NATO combat troops will leave Afghanistan as planned by the end of this year, but he intended to leave some 9,800 American soldiers behind to carry out training and counterterrorism missions.

Abdullah and Ahmadzai were the front-runners in the first round of election on April 5, but both failed to garner more than half of the votes to be a clear winner.

Afghan voters went to the polls on Saturday amid violence across the country, with more than 200 attacks leaving at least 30 people dead.