The US may have wasted millions of dollars on drones that have ineffectively patrolled the Mexico border, a scathing Homeland Security report has revealed.

The US Customs and Border Protection's (CBP) drone surveillance program — which allegedly helped law enforcement make only 2 percent of its border arrests in 2013 — follows a distressing pattern of rapid border security investment with little oversight, analysts told VICE News.

The report, released by the Department of Homeland Security's (DHS) Office of the Inspector General Tuesday, found that CBP spent at least $62.5 million on the program in one year.

DHS also found that CBP officials had vastly underreported the program's cost, claiming the unmanned aerial vehicles cost $2,468 per hour of flight time, while the inspector general calculated the real cost to be more than five times that amount, at $12,255 per hour.

"We see no evidence that the drones contribute to a more secure border, and there is no reason to invest additional taxpayer funds at this time," Inspector General John Roth said in a statement. "Securing our borders is a crucial mission for CBP and DHS. CBP's drone program has so far fallen far short of being an asset to that effort."

The inspector general's office further advised CBP to "reconsider its plan to expand" the drone program and planned additional investment of $443 million, "and put those funds to better use."

"The language of this government report is uncharacteristically blunt for a government report, and that evidences real concern from the inspector general," Mark Noferi, an enforcement fellow with the American Immigration Council, told VICE News, adding that the CBP exercised a concerning lack of discretion in operating its drone program.

The inspector general previously released a report on CPB's drone program back in 2012, which warned that the agency was "at risk of having invested significant resources in a program that… limits its ability to achieve Office of Air and Marine mission goals."

"We see this as part of a pattern," said Noferi of the latest report. "Border patrol is spending hundreds of millions and billions of dollars on increased enforcement, without evidence that increased enforcement is working the way it's intended to. There's been this explosion of border patrol funding, and often when they expand that rapidly there's inadequate oversight."

The drones further reflect the border agency's unwarranted reliance on military technology, Tony Payan, director of the Mexico Center at Rice University's Baker Institute for Public Policy, told VICE News.

"There is among border agencies, a desire to play with the latest toys developed by the military," Payan said. "They seem to have a penchant for trying to acquire hardware that doesn't really belong in the context of what they do."

Payan said that such technology, including heavy weaponry and military-style vehicles, "seems to distract [the agency] from their true mission, which is to ensure that the borders on the ground — the true threat — are fully protected and managed effectively."

CBP spokesman Carlos Lazo told VICE News Thursday that the inspector general's report was misleading and had inaccurately calculated the cost of operating the drones.

Lazo said the inspector general calculated an additional $10,000 per hour cost of the drones in his report, which included the salaries of multiple people involved in operating the technology. But those salaries had already been included elsewhere in CBP's budget, Lazo claimed.

As for the report's claims of the ineffectiveness of the program, Lazo argued that the aircraft were used to identify "hot spots" so border patrol agents could then move to arrest people on the ground.

"It's not a silver bullet, it's one of many pieces," Lazo said of a drone's role in patrol.

In a letter sent in response to the inspector general's assessment, CBP also denied that it was planning to add another 14 aircraft, as the report claimed, and said the additional $443 million in funds would instead be used to improve and maintain its current fleet of nine drones, and to replace a lost one.

The report also "overlooked" the significant accomplishments of the program, such as its role in the seizure of $122 million worth of marijuana and $562 million worth of cocaine on the Southwest border, the letter claimed.

But analysts maintain that using drones in border policing is an expensive strategy and that the program's small gains may not outweigh its hefty price tag.

"Unmanned systems operating on the border provide an additional layer of surveillance, but once a target is identified, additional assets — including conventional reconnaissance assets — are often queued to the area to examine the target," Bill French, a policy analyst for the National Security Network, told VICE News. "That additional layer of expensive, unmanned reconnaissance may simply not be worth it."

"Drones, despite their popular appeal, aren't a cure-all, and require the right operational niche, expertise and operational environment to be effective and worth the cost," he added.