Iran will receive the first $550 million installment of a total of $4.2 billion in previously blocked overseas funds on or about February 1, a senior U.S. official told Reuters on Sunday.
The money will be transferred to Iran as part of the implementation of the nuclear deal reached with it in Geneva on November 24.
Earlier Sunday, President Barack Obama confirmed that the agreement would be implemented starting January 20. Under the agreement, six major powers agreed to give Iran access to $4.2 billion in revenues blocked overseas if it carries out the deal, which offers sanctions relief in exchange for steps to curb the Iranian nuclear program.
Some payments are contingent on Iran diluting its stockpile of 20 percent enriched uranium to no more than 5 percent enriched uranium. The U.S. official, who spoke to Reuters on condition of anonymity, said that the first $550 million will be transferred February 1, and will be followed by another $450 million on March 1.
Other installments of $450 million and $550 million each will follow until July 20, the source said.
The official said immediate relief, which will hinge on UN inspectors confirming that Iran is curbing enrichment of uranium, would include imports for its auto manufacturing sector and trade in gold and other precious metals.
Shortly after the interim accord goes into force, an Iranian official said, the two sides will start negotiating a final settlement of their differences about activity the West suspects is aimed at obtaining a nuclear weapons capability.
European Union foreign policy chief Catherine Ashton also confirmed the January 20 implementation date, and said the sides would now ask the United Nations nuclear watchdog to verify the deal's implementation.
"We will ask the IAEA to undertake the necessary nuclear-related monitoring and verification activities," she said in a statement quoted by Reuters, referring to the International Atomic Energy Agency.
"Access to a portion of these funds will be linked to Iran's progress in completing the dilution process for 20 percent enriched uranium," the American official told the news agency.
"Iran will not have access to the final installment of the $4.2 billion until the last day of the six-month period."
The relief package would also entail allowing third-country purchases of Iranian oil to remain at current levels.
Meanwhile in the U.S., a bill to slap new sanctions on Iran if it goes back on the interim deal has gained support since it was introduced in December, aides to U.S. senators said last week.
The bill requires further reductions in Iran's oil exports and would apply new penalties on other industries if Iran either violates the interim agreement or fails to reach a final comprehensive deal.
President Obama is opposed to the bill and has threatened to veto it even if lawmakers pass it. Obama reiterated his objection to the bill in a statement he issued Sunday.