International donors meeting in Tokyo have pledged $16 billion in development aid for Afghanistan over the next four years.

The amount is in line with the $4 billion a year that Afghan President Hamid Karzai requested at Sunday's conference.

In his opening remarks, Mr. Karzai acknowledged that endemic corruption in Afghanistan has undermined previous aid efforts, and he promised to do more to bring that under control.

“Corruption in particular is a menace that has undermined the effectiveness, cohesion and legitimacy of our institutions. We will fight corruption with strong resolve wherever it occurs, and ask the same of our international partners. Together we must stop the practices that feed corruption or undermine the legitimacy and effectiveness of national institutions.”

The conference is attended by representatives of about 70 countries and senior world officials, including U.N. Secretary-General Ban Ki-moon and U.S. Secretary of State Hillary Clinton.