Iran would 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 US official said.

Under a November 24 nuclear 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 on condition of anonymity, described the payment schedule as follows:

Feb 1 - $550 million

March 1 - $450 million (payment for half of dilution);

March 7 - $550 million;

April 10 - $550 million;

April 15 - $450 million (payment for completion of dilution);

May 14 - $550 million;

June 17 - $550 million;

July 20 - $550 million  - Reuters