In a tweet late Thursday night, President Donald Trump without comment posted a link to the right-wing populist website Breitbart.

Only hours before, 49 people in New Zealand were killed in attacks on mosques, with one suspect described as an "extremist, right-wing" terrorist by Australia's prime minister.

Trump had conducted an interview with Breitbart published the previous day.

In the early hours of Friday morning the president deleted the tweet.

President Donald Trump early on Friday morning deleted a tweet linking to the Breitbart website, a tweet he posted just as the New Zealand mosque shootings were unfolding.

Breitbart is renowned for its hardline anti-Muslim and anti-immigration coverage.

In the now deleted tweet posted late on Thursday, Trump linked to Breitbart's homepage without comment.

Trump recently conducted an interview with Breitbart that had been published the day before.

The president did not specify what part of Breitbart he wanted followers to see at the time he posted the link.

Trump tweeted at about 11 p.m. Eastern time. By then, news outlets had been reporting on the shooting in New Zealand for about an hour. Breitbart was also running the story.

Critics questioned why Trump chose to link to the site, posting screenshots of anti-Islam comments underneath a Breitbart report on the attacks.

Breitbart was among the first to champion his hardline populist policies and was described by Steve Bannon, its former chairman, as a platform of the "alt right" nationalist movement.

Academic and Washington Post columnist Brian Klaas tweeted: "Trump could have not responded; responded gracefully; or linked to any other website about the NZ terror attack. He chose Breitbart."

MSNBC anchor David Gura commented: "Last night, hours after the terrorist attack in New Zealand, President Trump tweeted a Breitbart News article about the shooting, without comment. Moments ago, 11 hours after the attack, he posted his own tweet. The Breitbart News article no longer appears in his feed."

About 24 hours before Trump's tweet, Breitbart had published an interview with the president in which he warned that things could get "very bad" for his Democrat opponents if his supporters "get tough."

The White House did not immediately respond to a request for comment on the deletion of the tweet and criticism of the president. Breitbart also did not immediately respond to a request for comment.

The president early on Friday tweeted an official message of condolence to the victims of the attack, writing:

My warmest sympathy and best wishes goes out to the people of New Zealand after the horrible massacre in the Mosques. 49 innocent people have so senselessly died, with so many more seriously injured. The U.S. stands by New Zealand for anything we can do. God bless all!

Breitbart has long been accused of fostering anti-Islam views with its coverage and in February 2018 deleted a tweet in which it suggested that Muslims would end the Super Bowl if they controlled America.

In manifesto posted online before the shooting in New Zealand, a man reported to be the gunman praised Trump as a "symbol of renewed white identity" in a document filled with alt-right propaganda.