The U.S. Treasury Department on Monday, Feb 3, confirmed that it has allowed the transfer of $550 million in Iran's frozen oil revenues to the country under an interim nuclear deal, according to Reuters.

A U.S. Treasury spokeswoman said the transfer began Jan 31 and would be complete early this week but declined to specify which foreign banks were involved.

No U.S. banks were involved in the transactions, but the United States, which has extensive sanctions on Iran tied to its disputed nuclear program, helped facilitate the transfer of funds, the spokeswoman said.

The money is the first installment of $4.2 billion in blocked oil funds that were to be made available to Iran under the nuclear deal signed in November. Iran received limited sanctions relief in exchange for agreeing to curb its nuclear activities.