Mic reporter Emily Singer has apologized after mistakenly claiming Tuesday that alleged Russian agent Maria Butina was among a group photographed in the Oval Office in 2017. The woman in the photo turned out to be a National Security Council staffer.

Butina, 29, was arrested Sunday on a charge of conspiracy to act as an unregistered agent of the Russian government, according to court papers unsealed in Washington. She made her initial court appearance Monday afternoon, and was ordered held pending a hearing set for Wednesday.

Singer’s now-deleted tweet featured an image of Russian diplomat Sergey Lavrov’s group visiting Trump in the Oval Office in May 2017 with the caption, “I thought this was a photoshop, but it’s not. This is Maria Butina – arrested for being a Russian spy – in the Oval Office with Trump.”

The tweet was shared thousands of times before Singer realized that the woman in the photo is not a Russian spy.

“OK all, this may be Cari Lutkins from the NSC. I may delete this tweet,” Singer wrote before deleting it and adding, “I've deleted the tweet. I cannot confirm that it is Butina and may be an NSC staffer.”

The woman in the photo is Cari Lutkins, a National Security Council staffer.

“Singer’s evidence was that there was a redheaded woman (Butina is a redhead) standing in the back,” The Daily Caller’s Amber Athey wrote.

When reached by Fox News, Singer provided the following comment: “This morning I made a serious error in tweeting about a meeting in the Oval Office in 2017. The information was incorrect, and I deleted the tweet within an hour, as soon as I realized the mistake. I apologize for any confusion.”

While the now-deleted tweet was shared at least 3,800 times and liked at least 5,800 times, Singer’s tweets indicating it was not accurate had less than 200 retweets combined hours after she removed her original message. Twitter is now filled with dozens of threads falsely indicating that a Russian spy was in the Oval Office.

Singer is Mic’s senior writer on a beat called “Navigating Trump’s America.” Various media watchdogs have taken her to task.

“That is a major screw-up. It’s not merely a tweet. This was a reporter, treated credibly, retweeted credibly, saying that a Russian foreign agent was in the Oval Office,” Mediaite’s Caleb Howe wrote.

Mic declined comment when reached by Fox News.

Fox News’ Frank Miles and Greg Norman contributed to this report.