"So when you say corruption in highest government circles, you must mean something by that. What does that mean? Does it mean awarding contracts to relatives? Does it mean corruption in implementing projects? Does it mean all sorts of others, you know, nepotism and cronies? What does that mean?
"We have been discussing this for the past four to five years in the Afghan cabinet and government circles, and with the international community. Unfortunately, that is more a slogan. It doesn't come to giving us the details," he said.
Also on Monday, Afghanistan's ambassador to the United Nations, Zahir Tanin, said widespread criticism of the elections had strained ties with the international community.
"The United States and its allies came to Afghanistan after September 11. Afghanistan was troubled like hell before that too, nobody bothered about us"
"We will achieve nothing without the consistent political, military and financial support of the international community," Tanin said.
"Most importantly, we will achieve nothing without mutual understanding built on trust and co-operation."
"Recent public debate about Afghanistan has strained this understanding," he added.
Obama congratulated Karzai last week on being declared the winner of Afghanistan's presidential election, but said the re-election had "to be a point in time in which we begin to write a new chapter".
The US president said he had told Karzai that "the proof is not going to be in words, it's going to be in deeds".
The most senior US military officer also urged Karzai to tackle what he called the high level of corruption in the Afghan government.
"We are extremely concerned about the level of corruption and the legitimacy of this government ... It's far too much endemic," Admiral Michael Mullen, chairman of the US Joint Chiefs of Staff, said last week.
Karzai's re-election itself was called into question after a UN-backed polls watchdog said there had been widespread fraud in the first round, forcing him into a second round runoff.
But his last remaining rival, Abdullah Abdullah, pulled out of the runoff, citing the Karzai government's refusal to accept his demands for changes to the electoral commission.
Karzai said there was "the usual corruption in any government, especially in a third-world country like Afghanistan, with years of breakdowns and lack of governance, lack of institutions and lack of capacity".
Then there was "corruption of a different kind which is a lot more serious, which is new to Afghanistan - which is with the arrival of a lot of money to Afghanistan".
"The contractual mechanisms, the contracts that go from one to second to third to fourth, the lack of transparency in the award of contracts, the serious corruption in implementing projects, in buying bad quality material."
Karzai said that many multi-million dollar projects often end up under-funded, while a great deal of the money awarded in the original contract goes missing.
"A project that costs $10m actually receives $3m or $4m or even less than that," Karzai said.
"For that sort of corruption, it is the international community also that shares responsibility with us, and that is what I hope we can correct together."
With international pressure mounting on Karzai to take a firm stand against alleged corruption in government, the Afghan president said in the interview that the "the West is not here primarily for the sake of Afghanistan".
"It is here to fight the war on terror. The United States and its allies came to Afghanistan after September 11. Afghanistan was troubled like hell before that too, nobody bothered about us," he said.
"We were being killed by al-Qaeda and the terrorists before September 11th for years, tortured and killed, our villages were destroyed, and we were living a miserable life.
"The West didn't care nor did they ever come. Rather, they were asking us to make up with the Taliban and the terrorists and al-Qaeda."
Thousands of US and Nato troops are still in Afghanistan more than eight years after they invaded the country to topple the Taliban government.
UN pullout 'no impact'
While the Taliban was swiftly forced from power, it has staged regular attacks against the replacement government in Kabul and foreign troops.
Obama is now considering a request from the senior commander of US and Nato forces in Afghanistan to have up to 40,000 extra US troops deployed to the country, on top of a US military presence that is expected to reach 68,000 troops by the end of the year.
The United Nations recently ordered the temporary withdrawal of two-thirds of its staff amid fears that they would face a string of attacks by Taliban fighters, but Karzai said that the UN's move would have "no impact" on the country.
"They may or may not return. Afghanistan won't notice it. We wish them well wherever they are," he said.