The head of Iran's atomic energy agency did not explain why Iran was intensifying the exploration at home. Tehran has in the past denied its uranium stockpile was running low, as some international nuclear experts have concluded.
UN Security Council sanctions bar countries from selling uranium to Iran in response to its refusal to stop uranium enrichment, a process that can be used to produce fuel for power plants or material for bombs.
"The most important priority, after the Bushehr nuclear power plant, is the exploration and discovery of uranium throughout the country," the official IRNA news agency quoted nuclear chief Ali Akbar Salehi as saying.
The United States and other nations have tried to persuade Iran to stop enriching uranium out of concern Tehran is seeking a pathway to weapons production under the cover of its civil nuclear power program.
Iran denies such an aim and says it only wants to enrich uranium to fuel a future network of power plants.
With Russian help, Iran began loading uranium fuel into its first nuclear power plant in the southern city of Bushehr on Saturday after years of delays.
'We will enter into exploration work'
Salehi, who is also Iran's vice president, said only one-third of the country has been explored for uranium deposits. He said the Atomic Energy Organization of Iran will carry out exploration work anywhere it detects a uranium vein.
"With the assistance of President (Mahmoud Ahmadinejad) and the allocation of a budget, we hope to survey the whole country as far as uranium exploration is concerned," Salehi was quoted by IRNA as saying. He didn't elaborate but said the study and exploration activities throughout Iran may take eight years.
"Anywhere there is a vein of uranium, we will enter into exploration work," the Iranian government website quoted Salehi as saying.
International experts have said Iran's stockpile of uranium oxide - used to make the gas that is spun through centrifuges in the enrichment process - appears to be rapidly diminishing.
In December, a confidential intelligence report drawn up by a member of the UN's nuclear watchdog agency said Iran was trying to secretly import 1,350 tons of uranium oxide from Kazakhstan for $450 million.
Iran at the time called the report "a fabrication and completely baseless."
Tehran still has hundreds of tons of the uranium hexafluoride gas used in the enrichment process.
The UN's International Atomic Energy Agency believes Iran's rapidly expanding enrichment program has been built on 600 tons of uranium oxide imported from South Africa during the 1970s as part of plans by the US-backed shah to build a civil nuclear power program.
The Washington-based Institute for Science and International Security said last year that, based on 2008 IAEA statistics, Iran had already used up close to three-quarters of its South African supply.
Iran's own principal source of uranium is the Saghand mine in the center of the country, which has the capacity to produce 132,000 tons (120,000 metric tons) of ore per year. Located about 300 miles (480 kilometers) south of Tehran, the mine consists of an open pit with minimal reserves and a deep mine. It has a total estimated uranium ore reserve of 1.73 million tons (1.58 million metric tons).
It also has smaller uranium deposits near the southern port city of Bandar Abbas where a mill is reportedly converting raw uranium into uranium ore concentrate known as yellowcake.
Iran announced discoveries of new uranium deposits in 2006 at three sites in the central Khoshoomi, Charchooleh and Narigan areas.