Donald Trump addresses the nation from the Oval office

US President Donald Trump repeated his demand Tuesday for $5.7 billion to fund a wall on the border with Mexico, describing a "growing crisis" of illegal immigration hurting millions of Americans.

In his first ever televised Oval Office address, the president stopped short of calling for a much-touted state of emergency, instead appealing to the need to slash the cost of the illegal drug trade, which he put at $500 billion a year.

"There is a growing humanitarian and security crisis at our southern border. Every day customs and border patrol agents encounter thousands of illegal immigrants trying to enter our country," Trump said.

"We are out of space to hold them and we have no way to promptly return them back home to their country. America proudly welcomes millions of lawful immigrants who enrich our society and contribute to our nation. But all Americans are hurt by uncontrolled illegal migration."

Trump had spent days mulling declaring a state of emergency along the border that would have given him powers to bypass Congress, which has so far refused to fund the wall project, and draw funds from the military to build the border barrier.

He didn't mention the idea in his nine-minute address but repeated his call for a wall and spoke of an "overall approach" that would use technology for detecting drugs and weapons.

"At the request of Democrats, it will be a steel barrier rather than a concrete wall. This barrier is absolutely critical to border security. It's also what our professionals at the border want and need," he said.