US President Donald Trump has sparked controversy in the Middle East by accusing Kurdish groups in the region of withholding weapons that were intended for Iranian demonstrators.

In early March, at the start of the US-Israeli war with Iran, Trump said it would be "wonderful" if Iranian Kurdish forces based across the border in Iraq launched attacks against the Islamic clerical regime in Tehran.

The following month, Trump told Fox News that the United States had tried to send weapons to protesters inside Iran through Kurdish intermediaries.

"We sent guns to the protesters, a lot of them," Trump said. "And I think the Kurds took the guns."

In May, he said he was "very disappointed in the Kurds," adding that Washington had sent "some guns with ammunition, and they were supposed to be delivered, but they kept it."