(Reuters) – India has once again delayed the implementation of higher tariffs on some goods imported from the United States to May 15, a government official said on Friday.

The new tariff structure was to come into force from May 2, the spokeswoman said without citing reasons for the delay.

Angered by Washington’s refusal to exempt it from new steel and aluminum tariffs, New Delhi decided in June last year to raise the import tax from Aug. 4 on some U.S. products including almonds, walnuts and apples.

But since then, New Delhi has repeatedly delayed the implementation of the new tariff.

Trade friction between India and the U.S. has escalated after U.S. President Donald Trump announced plans earlier this year to end preferential trade treatment for India that allows duty-free entry for up to $5.6 billion worth of its exports to the United States.

In a further blow, U.S. on Monday demanded buyers of Iranian oil stop purchases by May or face sanctions, ending six months of waivers which allowed Iran’s eight biggest buyers including India to continue importing limited volumes.