Updated

The Obama administration has exempted China and Singapore from economic sanctions because they have significantly reduced imports of Iranian oil.

The decision by Secretary of State Hillary Rodham Clinton spares Chinese and Singaporean banks from potentially being cut off from the American financial system. The sanctions are aimed at pressuring Iran to prove it is not trying to develop nuclear weapons.

The deadline for countries to stop buying Iranian oil went into effect Thursday. Seventeen countries already have received waivers from the U.S. to continue importing oil.

U.S. officials say Iran's oil exports have declined to less than 1.8 million barrels a day from 2.5 million barrels last year, reducing a main source of revenue for the regime.

Iran insists its nuclear program is peaceful.