About 40 of the additional military personnel will be Air Force intelligence analysts, while some 590 will be Army engineers, US Northern Command (NORTHCOM) said in a statement.

"The deployment of these units will increase the total number of troops deployed or scheduled to deploy to the southern border to approximately 9,600," NORTHCOM said.

"The exact number of personnel will fluctuate as units rotate personnel and as additional forces are tasked to deploy once planning efforts are finalized," it added.

Border security is a key priority for President Donald Trump, who declared a national emergency at the US frontier with Mexico on his first day in office on January 20.

The Trump administration has launched what it cast as a major effort to curb illegal migration that has included immigration raids, arrests and deportations.

The president hailed his border security efforts earlier this month, posting on his Truth Social platform that "the Invasion of our Country is OVER."

"Thanks to the Trump Administration Policies, the Border is CLOSED to all Illegal Immigrants," Trump wrote.