The arrest at a US border of a researcher allegedly trying to smuggle non-infectious Ebola DNA in from Canada is raising questions about high-containment lab security.

But officials on both sides of the border are saying little about how the samples were removed from the Canadian National Microbiology Laboratory in Winnipeg, or about the suspect, 42-year-old Konan Michel Yao, who was a fellow at the laboratory until January.

On 5 May, Yao was discovered to have 22 vials of Ebola genetic vectors as he tried to drive into North Dakota. He was charged three days later with smuggling biological material and making false statements to authorities. The incident became public only last week.

Yao, now a Canadian citizen but born in Ivory Coast, told US agents that he was heading to a fellowship at the National Institutes of Health (NIH) in Bethesda, Maryland, and had documents indicating this to be the case, court records say.

An NIH spokeswoman refused to discuss the case. Canadian government officials didn't respond to an inquiry.