WASHINGTON, June 29 (Reuters) - U.S. President Donald Trump has authorized the temporary suspension of certain duties on phosphate fertilizer imported from Morocco, the White House said on Monday, as farmers grapple with fertilizer shortages due to the Iran war.

White House economic adviser Kevin Hassett said in March the Trump ​administration was seeking more sources of fertilizer. Supply from major producers in the Middle East was sharply cut by the closure of the Strait of Hormuz.

"Global supply chains for phosphate fertilizer and fertilizer inputs, including imports of such products into the United States, have been disrupted in recent months by, among other things, conflicts in fertilizer-producing regions as well as trade actions taken by major fertilizer-producing countries," Trump said in a proclamation released by the White House.

Currently, U.S. production of phosphate fertilizer is insufficient to support domestic agricultural food production after accounting for exports, Trump said in the proclamation.

The Trump administration is working with the private sector to expand domestic fertilizer manufacturing capacity, but those efforts will take time to increase the supply materially, the president said, adding producers in countries like Morocco can supply phosphate fertilizers to the U.S. without disruption at this time.