Washington: US president Donald Trump will ask Congress for $1.5 billion to begin work on the wall he promised to build along the Mexico border, the media reported.

Washington: US president Donald Trump will ask Congress for $1.5 billion to begin work on the wall he promised to build along the Mexico border, the media reported.

The money is part of a $30 billion supplemental spending request being sent to lawmakers, according to White House budget director Mick Mulvaney.

Mulvaney told the media on Wednesday that the money would be used to begin developing technologies and locations for the wall, The Hill magazine reported.

The request also boosts funding for defence and other border security measures Trump has called for as part of a push to ramp up deportations of people living illegally in the US.

"I think the funding provides for a couple of pilot cases... different kinds of barriers in different kinds of places," the budget director said.

"We try and find the most cost-efficient, the safest and also the most effective border protections."