KABUL, Afghanistan — Afghan officials released preliminary election results Monday showing a switch in voting for president from the first election on April 5.

Now former finance minister Ashraf Ghani Ahmadzai is well in the lead for the presidency but officials said no winner can be declared because millions of ballots were being audited for fraud.

The announcement came as Ahmadzai is locked in a standoff with his rival Abdullah Abdullah, who has refused to accept any results until all fraudulent ballots are invalidated. A spokesman for his campaign rejected the results and called the decision to release them “a coup.”

The results showed that Ghani had about 4.5 million votes, or 56 percent, while Abdullah had 3.5 million votes, or 44 percent, according to the commission. Turnout was more than 50 percent.

Abdullah, a former foreign minister who won the first round of voting on April 5 by a large margin, says his campaign monitors recorded ballot box stuffing and other irregularities, prompting him to suspend his cooperation with electoral officials.

The Independent Election Commission acknowledged that vote rigging had occurred and said ballots from about 7,000 more of the nearly 23,000 polling stations would be audited.

The European Union expressed concern about “highly worrying indications of potentially widespread fraud.”

The United States issued a strongly worded statement cautioning the results “are not final or authoritative” and urging electoral authorities to “implement a thorough audit whether or not the two campaigns agree.”