WASHINGTON (Reuters) - Haiti's decision to scrap the results of a disputed first-round presidential vote will prolong an already delayed process at a time the country needs a democratically elected leader, the State Department said on Wednesday.

"The United States regrets that the electoral process is extended yet again with the president-elect unlikely to be installed before Feb. 7, 2017," State Department spokesman Mark Toner said.

"Our concern is that now taking this back to zero ... will add to the length of the process and there needs to be leadership installed there," he added.

The country's electoral council on Monday scrapped the results of the first round of Haiti's vote after a commission found evidence of fraud.

The first round vote was in October, but a second-round run-off was postponed several times. Interim President Jocelerme Privert has said he will stay in office until next year to transfer power to an elected president unless parliament rules otherwise.

Supporters of Privert and his allies say that international pressure to hold a vote quickly led to the flawed first round. Others say the vote should go ahead quickly to help the country recover from the devastating 2010 earthquake and food shortages.

(Reporting by Lesley Wroughton; EDitin by Steve Orlofsky)