Truckers blaring their horns outside the White House Friday interrupted a press briefing by US President Donald Trump, who welcomed their protest at low shipping rates during the coronavirus pandemic.

"That's the sign of love," said Trump from the podium in the White House grounds, referring to the honking that he called "that beautiful sound."

"They're protesting in favor of President Trump, as opposed to against him," he said.

Dozens of large trucks have been parked for days outside the White House in the heart of Washington.

The truckers are demanding the administration address the issue of low freight shipping rates, which they say are putting their business at risk. 

The protest came as trucking companies play a vital role in keeping the virus-struck nation's stores supplied, as tens of millions of Americans shelter at home.

Some of the drivers had rolled out banners Friday that read "Make American Trucking Great Again," a riff on Trump's 2016 campaign slogan.

"Don't let brokers kill the trucking industry," read another sign on one of the rigs parked on the road that runs along the southern edge of the White House grounds.