The Department of National Defence may have dug up and disposed of barrels containing chemicals at a New Brunswick military base decades ago — but they're not the ones at the centre of a renewed controversy over Agent Orange use at CFB Gagetown, said a former civilian employee of the department.

Robert Wilcox told CBC News that he was present when chemical drums were buried and when they were later dug up again in an area of the base known as the Shirley Road dump.

The claim this week by retired military police sergeant Al White — who said he witnessed the burial of at least 40 barrels of the toxic defoliant in late spring 1985 — represents something entirely new and significant, said Wilcox.

"I think there's more out there," he told CBC News in an interview.

Defence Minister Harjit Sajjan said Wednesday his department is looking into White's allegation, but insisted the base in southwestern New Brunswick — one of the largest combat training centres in the country — is safe.

"A lot of extensive work has been done," Sajjan said. "Independent research, with the right experts, has been conducted. A lot of the Agent Orange, those drums people talk about, have been removed."

The excavation Sajjan spoke of also took place in 1985 and involved the recovery of 637 uncrushed barrels — 104 of which contained some form of "liquid," according to DND — and another 135 drums that had been crushed.

Wilcox said he was there when many of those barrels were buried in 1975. He claimed the department only dug them up 10 years later because an excavator had uncovered the area by mistake.

Agent Orange is a toxic defoliant used by the U.S. military in the Vietnam conflict. It was sprayed at CFB Gagetown in 1966 and 1967 as part of a secret program run by the U.S. military, with permission from Canada.

'Do a proper job'

Exposure to the defoliant can lead to skin disorders, liver problems and certain types of cancers. After years of stonewalling by National Defence, the former Conservative government set aside almost $100 million in 2007 for Canadians who demonstrate health conditions related to the use of defoliants.

Ottawa also reversed a decision to reject compensation for dozens of soldiers and their families exposed to the defoliant who later became ill.

Carol Parker-Brown represents the Agent Orange Association, which still lobbies for more federal disclosure on the program. She said the separate eyewitness accounts offered by Wilcox — who worked for the department for 35 years — and White suggest that Agent Orange was buried in more than one spot on the base.

That, she said, should be all the federal government needs to know to order a deeper investigation.

"I think it's definitely important," said Parker-Brown. "They didn't do a thorough job in the first place and they should come back and do a proper job."

DND conducted soil tests at Gagetown more than a decade ago and found 10 areas deemed to have unacceptable levels of chemicals related to the aerial spraying program. The grounds were remediated, according to department records.

The risk of contamination from long-buried drums could be more significant than the contamination identified by those soil tests, said Brown-Parker, adding the problem calls for deep core sampling and not just "prettying up."

'We are looking into this'

Sajjan would not say precisely what kind of review the department will undertake.

"Right now, based on your story, we are looking into this," the minister told CBC News following question period.

CBC News asked for access to the base so White could show defence officials where he saw the barrels being buried. The request was denied. Sajjan showed no sign Wednesday of reversing that decision.

Late Wednesday, White said he had not heard from defence officials.

White told CBC News he didn't come forward about the burial at the time because he didn't believe it was his secret to share.

That changed when he lost three friends — all Gagetown soldiers — to cancer.

Wilcox, who applied and was rejected under Ottawa's compensation program, has lobbied both Sajjan and former Veterans Affairs minister Kent Hehr to reopen the investigation into what happened at the base.

"The research confirmed that the base is safe and that the majority of people did not experience long-term health effects from the testing that was done," Hehr wrote on June 23, 2016.

Wilcox said that's unacceptable.

"A lot of people around here died at a young age, especially from the base," he said.

"Yes, there (are) more barrels out there."