A Pentagon plan to create an overseas intelligence agency is being trimmed after lawmakers voiced concern with its price and purpose, The Washington Post reported.

The new Defense Clandestine Service, announced by the Pentagon more than two years ago, is to use existing agents, authorities and assets and work closely with the Central Intelligence Agency to track emerging threats.

But a report by the Post late Saturday said that the US military's Defense Intelligence Agency would train and deploy at most only 500 undercover officers, approximately half of what was initially planned.

Cutbacks also include a scaled-down training schedule and steering most of those involved towards more traditional DIA roles.

Although case officers from the DIA already secretly gather intelligence outside of conventional battle zones, the Defense Clandestine Service, or DCS, is meant to further cement cooperation between the military and the CIA.

But Congress, including members of the Senate Armed Forces Committee in particular, voiced concern that the Pentagon would be picking up the tab for CIA duties, the Post said.

"We did reevaluate the DCS program after initial discussions with Congress," Pentagon spokeswoman Navy Commander Amy Derrick-Frost said in the Post.

The former head of the DIA, Lieutenant General Michael Flynn, was pushed out of his post earlier this year, according to the Post, after disagreements with other senior figures and amid efforts to speed up the plan to deploy more spies.