WASHINGTON, Jan. 20 (Xinhua) -- The United States on Monday started to ease some of the economic sanctions on Iran after the Islamic republic has taken "concrete actions" in curbing its controversial nuclear program.

U.S. Secretary of State John Kerry has approved waivers that offer limited sanction relief on Iran's oil exports, financial transactions and trade in gold and precious metals, among others, the State Department said.

The United States has "taken the necessary steps to pause efforts to further reduce Iranian crude oil exports," allowing the six current customers of Iranian oil to maintain their purchases at current reduced levels for the six-month duration of an interim deal on Iran's nuclear program, the State Department said in a statement.

"Iran has begun to take concrete and verifiable steps to halt its nuclear program," spokeswoman Jen Psaki said in a separate statement.

Iran's actions represent "an important step forward" in halting its nuclear program, the White House said in a statement.