Waheed Omar told reporters the findings were made by the U.S. Geological Survey under contract to the Afghan government.
"The result of the survey ... has shown that Afghanistan has mineral resources worth $1 trillion," Omar said. "This is not an overall survey of all minerals in Afghanistan. Whatever has been found in this survey is worth $1 trillion."
Omar refused to provide details, referring reporters to the Ministry of Mines. An official at the ministry refused to discuss the survey, saying details would be released at a news conference later this week.
A 2007 report by the USGS said most of the data on Afghanistan's mineral resources was produced between the early 1950s and 1985 but much was hidden and protected by Afghan scientists "during the intermittent conflict over the next two decades."
The New York Times reported the $1 trillion figure in Monday's edition and quoted senior American officials as saying untapped mineral deposits in Afghanistan are far beyond any previously known reserves and were enough to fundamentally alter the Afghan economy and perhaps the Afghan war itself.
Americans discovered nearly $1 trillion in untapped mineral deposits in Afghanistan, including iron, copper, cobalt, gold and critical industrial metals like lithium, according to the report. The Times quoted a Pentagon memo as saying Afghanistan could become the "Saudi Arabia of lithium," a key raw material in the manufacture of batteries for laptops and cell phones.
"There is stunning potential here," the newspaper quoted Gen. David H. Petraeus, commander of the United States Central Command as saying. "There are a lot of ifs, of course, but I think potentially it is hugely significant."
Geologists have known for decades that Afghanistan contained substantial mineral resources, including copper, gold and cobalt. But the resources have never been fully exploited because of decades of armed conflict and poor infrastructure. The Times said huge lithium deposits were found in Ghazni province — much of which is effectively under Taliban control.
During a visit last month to Washington, Karzai said his nation's untapped mineral deposits could be even higher — perhaps as much as $3 trillion.
The mineral resources are a "massive opportunity," Karzai said at a May 13 event with Secretary of State Hillary Rodham Clinton held at the U.S. Institute of Peace.
The report in the Times said the USGS began aerial surveys of Afghanistan's mineral resources in 2006, using data that had been collected by Soviet mining experts during the Soviet occupation of Afghanistan in the 1980s. Promising results led to a more sophisticated study the next year.
Then last year, a Pentagon task force that had created business development programs in Iraq arrived in Afghanistan and closely analyzed the geologists' findings. U.S. mining experts were brought in to validate the survey's conclusions, and top U.S. and Afghan officials were briefed.
"I think it's very, very big news for the people of Afghanistan and that we hope will bring the Afghan people together for a cause that will benefit everyone," Karzai's spokesman, Omar, said. "This is an economic interest that will benefit all Afghans and will benefit Afghanistan in the long run."
So far, the biggest mineral deposits discovered are of iron and copper, but finds include large deposits of niobium, a soft metal used in producing superconducting steel, as well as rare earth elements and large gold deposits in Pashtun areas of southern Afghanistan, the report said. Many of those areas are too dangerous because of Taliban activity.
Charles Kernot, a mining analyst with Evolution Securities Ltd. in London, said it typically takes three to five years to get a lithium mining operation up and running. Factors include how close the deposit is to power sources and other infrastructure and the size of the deposit.
And large lithium deposits may not mean an automatic windfall — given competition and the uncertainty of the market.
"Bolivia wants to expand its lithium mining operations dramatically over the next few years so there is a risk of oversupply if demand from electric cars does not meet expectations," Kernot said.