Trump inauguration crowd
Photos taken at the National Mall show the crowds attending the inauguration ceremonies to swear in US President Donald Trump, left, on 20 January 2017 and Barack Obama, right, on 20 January 2009, in Washington, DC Reuters

President Donald Trump was said to be "directly involved" in the quest to find the staff member from the National Park Service (NPS) who retweeted a photo that compared the size of his inauguration crowd with that of his predecessor, Barack Obama.

On the day of Trump's inauguration, the photo on the official NPS account showed the crowd for Obama's event was bigger than that of Trump.

The retweet was taken down, but not after the image had gone viral around the world.

According to a report from CBS News, who cited emails about the exchange released through the Freedom of Information Act, Trump contacted acting NPS director Mike Reynolds about the tweet.

"This has become a very sensitive issue, especially since the President has gotten directly involved and contacted Acting Director Mike Reynolds concerned about one of the images that was retweeted," NPS chief of digital strategy Tim Cash wrote to NPS chief information security officer Shaun Cavanaugh on 21 January, according to CBS News.

The Washington Post reported the contact between Trump and Reynolds in January, but neither the NPS or the White House confirmed it.

Trump claimed on several occasions that his inauguration had the largest crowd in US history.

Trump's press secretary, Sean Spicer told reporters that Trump drew "the largest audience ever to witness an inauguration, period, both in person and around the globe."

This was then described by senior adviser to Trump Kellyanne Conway as providing the media with "alternative facts".

Trump said that the media's reports on his crowd size was an effort to "demean" him.