Karzai has been under pressure to address widespread corruption and bribery since he was re-elected after a poll marred by widespread fraud.
After Karzai was declared the victor, following the withdrawal of his main rival from a planned second round runoff, the United States, Britain and other countries warned that the president could not expect unending, unconditional support.
Clinton also addressed criticism from Karzai, who suggested that the donor countries should be responsible for tracking where their money goes, condemned civilian casualties in military operations and spoke of the mistreatment of detainees.
"As we call for accountability from others, we will hold ourselves accountable as well," Clinton said.
"We are working to ensure that development funds are tracked, accounted for and used as intended, that our detention facilities and procedures are consistent with our security and our values, that we do everything we can to minimize civilian casulaties."
A spokesman for Gordon Brown, the British prime minister, said the speech "offers hope for the Afghan people".
"We believe that Karzai set out today a clear commitment to deliver in the areas which [Brown] highlighted as being crucial for the new government to tackle."
"There are very clear expectations of Karzai's second term on the part of the entire international community. We now want to see Karzai deliver for all Afghans, and we will work with him to ensure that he does," Brown's spokesman said on Thursday.
Earlier this week, Afghanistan announced it was setting up a new anti-corruption unit and Karzai said that there would be a conference on corruption in Kabul in the coming months.
At the ceremony in Kabul, Guido Westerwelle, the German foreign minister, said: "This was a speech with the right emphases. It fulfilled our expectations."
"We will take President Karzai at his word and expect that the right words will be followed by the right doings."
Westerwelle's remarks were echoed by Ettore Sequi, the European Union respresentative at the ceremony, who called the speech "a very good statement which reflected the right priorities the right way".
"Let's encourage and support the president and we shall have opportunities to see how that programme will be translated into reality," he said.
Sequi said that the first test of Karzai's will would be his choice of cabinet ministers, which is expected to be announced in the coming weeks.
Karzai on Thursday promised to appoint "competent and professional" ministers.
Anders Fogh Rasmussen, the Nato secretary -general, offered his "best wishes" to Karzai for the next five years.
|Clinton said that Karzai's speech was 'particularly strong' on corruption [AFP]
"We strongly support his intention to form a capable and inclusive administration, and to make it accountable, one in which corruption has no place," he said.
"It is critically important that the Afghan people, and the citizens of the countries sending troops to the international mission, see concrete progress in this regard."
Nato leads the International Security Assistance Force (Isaf) which has about 70,000 troops from more than 40 nations fighting in Afghanistan.
Rasmussen said the Isaf forces would "work with the new government to enable the Afghan national security forces to assume lead responsibility for their country's security, district by district and province by province, when conditions permit".
Karzai has said he hopes that Afghanistan's own security forces can take responsibility for the entire country within five years, after taking the lead in unstable areas within three years.
It is a goal that will be popular with his Wetsrn allies, who are desperately seeking an exit strategy from the eight-year war as it becomes increasingly unpopular with their domestic audiences.