"We are not cooperating with Iran in this field [export and reprocessing of uranium], there is no discussion of this yet," Khikmatullo Nasrulloyev said.

Nasrulloyev said that a dozen waste storage sites with a capacity of some 50 million tons of radioactive waste are located in northern Tajikistan.

"Many of these storage sites are not protected and located next to residential housing, whose residents constantly receive doses of radiation 20 times above the established health standards," the scientist said.

Some $45 million is required to ensure security of these dumps, he said adding that Tajikistan has received $30 million under a joint project between Tajikistan and the EuroAsian Economic Community.

Four times, in 2004, 2006, 2008 and in 2009 attempts to sell and export radioactive sources from Tajikistan were rebuffed, the country's Emergency Situations Committee radiology laboratory chief Todzhiddin Makhmadov said.

Tajikistan supports Iran's right to develop a peaceful nuclear program, Tajik Foreign Minister Khamrokhon Zarifi said last month.

An Iranian official reaffirmed Tehran's commitment to begin construction of a new uranium enrichment center in 2011. Iran plans to build a total of ten such centers in the future.

Western powers suspect Iran of seeking to build nuclear weapons under the guise of its nuclear program, which Tehran says is aimed at the peaceful generation of civilian energy.

Senior diplomats from the Iran Six met Iranian officials in Geneva last October to discuss an agreement on a nuclear fuel swap, but the agreement eventually fell through.

The draft agreement proposed by former IAEA chief Mohammed ElBaradei would have seen Iran send out about 80% of its known 1.5 metric tons of low-enriched uranium to Russia, where it would have been enriched, and to France to convert it into fuel plates for the research reactor in Tehran.

International pressure on Iran increased in early February when Tehran announced it had begun enriching uranium to 20% in lieu of an agreement on an exchange that would provide it with fuel for a research reactor.

Turkey, Brazil and Iran signed an agreement on May 17, dubbed the Tehran Declaration, in which Iran committed itself to giving 1,200 kg of its 3.5%-enriched uranium to Turkey in exchange for 20%-enriched uranium it would receive from Western countries to be used as fuel in the nuclear research reactor near Tehran.

The trilateral deal did not stop the UN Security Council from passing on June 9 a resolution imposing a fourth set of sanctions on Iran over its nuclear program.