WASHINGTON (Reuters) -The U.S. military is preparing to temporarily remove its humanitarian pier off the coast of Gaza because of anticipated sea conditions, a U.S. official said on Friday, the latest challenge to the effort that has been hampered by bad weather since it was put into place in May.

The floating U.S. military pier off Gaza had just resumed bringing humanitarian aid into the enclave after being suspended over the weekend.

The official, speaking on the condition of anonymity, said that the pier would likely be moved to the Israeli port of Ashdod until sea conditions improve.

Aid began arriving via the U.S.-built pier on May 17, and the U.N. said it transported 137 trucks of aid to warehouses, some 900 metric tons, before the U.S. announced on May 28 that it had suspended operations so repairs could be made.

The United Nations said on Friday it had still not resumed transportation of aid from the pier to U.N. World Food Programme warehouses.

"Our security colleagues are still working to ensure that secure conditions for humanitarian work can be re-established," said deputy U.N. spokesperson Farhan Haq.

U.S. President Joe Biden announced in March the plan to put the pier in place for aid deliveries as famine loomed in Gaza, a Hamas-run enclave of 2.3 million people, during the war between Israel and the Palestinian militants.

The pier is estimated to cost hundreds of millions of dollars for the first 90 days and involve about 1,000 U.S. service members.

(Reporting by Idrees Ali and Phil Stewart. Additional reporting by Michelle NicholsEditing by Alistair Bell)