BERLIN - The United States and Germany are stepping up pressure on Afghan President Hamid Karzai to implement major reforms and crack down on rampant corruption.

U.S. Secretary of State Hillary Rodham Clinton and German Foreign Minister Guido Westerwelle said Monday that international assistance to Afghanistan depends on Karzai improving the quality of his government and delivering needed services to the Afghan people.

After talks in the German capital, Clinton and Westerwelle also renewed warnings to Iran that unless it comes clean on its suspect nuclear program, it faces the prospect of additional sanctions.