JK Rowling has apologised for wrongly accusing Donald Trump of ignoring a disabled boy last week.

The "Harry Potter" author tweeted a clip of the US president, which appeared to show him ignoring a young boy in a wheelchair visiting the White House.

In a string of now deleted tweets, Rowling savaged Trump's "stunning" and "horrible" behaviour. Here is the thread in full, courtesy of Wayback Machine:

The problem? Rowling appeared not to have watched the entire news conference.

A video of the full event, posted on YouTube by the White House on July 24, shows the president bending down to greet three-year-old Montgomery Weer.

According to the Washington Post, Weer has Spina Bifida, a birth defect that prevents babies from developing their spine and can cause brain damage.

Trump and Vice President Mike Pence had given the news conference to urge Senate Republicans to repeal and replace the Affordable Care Act, or Obamacare.

They then stood in front of a group of families, including Weer and his mother, that Trump labelled Obamacare's "forgotten victims."

You can see the moment Trump greets Montgomery around the 2:20-minute mark here:

Rowling was corrected by Weer's family. Marjorie Kelly Weer, Montgomery's mother, wrote on Facebook that Trump "didn't snub [her] son" and that Montgomery was "showing off his newly acquired secret service patch," not trying to shake the president's hand.

"Good Morning Britain" presenter Piers Morgan tweeted Weer's Facebook post on 30 July.

He then used his MailOnline column on Monday to criticise Rowling's actions. He called her "the world's most aggressively self-righteous tweeter" and "a shameful, disgraceful hypocrite."

Later on Monday, Rowling acknowledged her error. The writer said she "very clearly projected my own sensitivities around the issue of disabled people being overlooked or ignored onto the images I saw and if that caused any distress to that boy or his family, I apologise unreservedly."

Rowling did not direct her apology toward Trump, and a spokesperson for the author declined to tell CNN whether she would do so.

She has also deleted her July 28 thread. The first in that series of July 28 tweets garnered more than 75,000 retweets by Monday, CNN noted. Chelsea Clinton originally retweeted Rowling's posts, but later undid the actions.

Rowling is not a stranger to Trump-bashing on Twitter. She has called out Trump for misquoting Mayor of London Sadiq Khan following the London Bridge terror attacks and encouraged anti-Trump protests if he ever visited Britain.

She also has a long running feud with Morgan.