Washington, Mar 28 (IANS): President Donald Trump's administration wants the first $1 billion of border wall funding to cover 62 miles, including replacing some existing fencing along the US' southern border with Mexico, a media report said.

The $999 million requested by the White House in its budget supplement for just defence and border security spending would cover just 48 miles of the new wall, CNN quoted justification documents from the Department of Homeland Security as saying.

The administration requested $1 billion in its supplemental for 2017, and another $2.6 billion for border infrastructure and technology in 2018.

The documents describe exactly where the administration hopes to put its first instalment of the border wall.

The money will fund 14 miles of new border wall in San Diego, 28 miles of new levee wall barriers and six miles of new border wall in the Rio Grande Valley region and 14 miles of replacement fencing in San Diego.

The fencing would likely include concrete elements, an official familiar with the plans told CNN.

Estimates for a full wall along the Southern border have ranged from $12 billion to more than $20 billion.

The documents also claim that Trump's executive orders on immigration enforcement were already having an effect, saying arrests have increased to 50 per cent and requests to detain arrested individuals who are deportable rose to 80 per cent.