Washington, May 11 (IANS): Acting US Defence Secretary Patrick Shanahan, has notified Congress that he intended to shift $1.5 billion that had been designated for the Afghanistan war and other projects to help pay for work on President Donald Trumps proposed border wall.

The money from the Pentagon's other programmes will be the last that it moves to help build about 80 miles of fencing and barriers along the southern border, The New York Times quoted Shanahan as saying on Friday.

The newest shift in funding is in addition to the $1 billion that the Defence Department transferred to wall construction in March from the Army's personnel budget.

Shanahan insisted that the budget transfer would not affect "readiness" -- the military catchall term that refers to the ability of American troops to fight when called up.

But some of the funds "did come from money we were under-running or saving or whatever, you know, terminology you want to use, from Afghanistan", he added.

In a letter to Shanahan later on Friday, several Democratic senators sharply criticised the diversion of funds from the Afghan war effort.

"Once again, the Department of Defence has ignored decades of precedent and cooperation with the Congress in carrying out a transfer of funds without regard to any consultation with the Appropriations Committee," said the letter.

"We are dismayed that the department has chosen to prioritize a political campaign promise over the disaster relief needs of our service members."

The Pentagon had planned to spend $4.9 billion in Afghanistan - primarily to support Afghan security forces who have struggled to hold parts of the country beyond Kabul from Taliban militants.

American officials said that the $600 million that was being diverted to the border is coming from savings that officials found in contracts.