Crude prices have tumbled more than one dollar per barrel after Iran and the P5+1 Group of countries reached a final deal over Tehran's nuclear program, Press TV reported.

Brent crude fell 1.6% or $1.70 to $57.06 a barrel on Monday.

Meanwhile, West Texas tumbled $1.15 to $51.59 a barrel.

Iran sits atop the world's 4th largest oil reserves and the second largest gas reserves.

Iran has been subject to unilateral Western sanctions over its nuclear program since 2012 which have seen the oil-rich country’s crude exports drop by more than 50%.

Tehran is estimated to hold 30 million barrels of crude in storage.

Oil prices are expected to further decrease if Iran and the six world powers mange to secure a final nuclear deal, under which, sanctions, including sanctions against the country's energy sector, will be lifted.