OTTAWA — The arrest of a Canadian intern accused of spying inside NATO’s military headquarters is putting Canada’s security-screening system under scrutiny after official rules showed she would have required national clearance before beginning the position.Belgian authorities allege the Canadian citizen of Chinese origin spied on behalf of an unidentified third country while working at Supreme Headquarters Allied Powers Europe, known as SHAPE, in the Belgian city of Mons.She is also accused of participating in a criminal organization. The allegations have not been proven in court.The Belgian Federal Prosecutor’s Office said SHAPE security services first noticed the suspect and reported the matter to Belgium’s General Intelligence and Security Service.Belgian federal police searched her home and workplace July 23. .An investigating judge ordered her detained the following day on suspicion of espionage and participation in a criminal organization.NATO’s published internship rules state that successful applicants receive only conditional offers until they obtain security clearance through their country’s national delegation.“You must gain a security clearance prior to the start of your internship,” the rules state.NATO says the process varies between countries but normally takes six to eight months.Canadian Security Intelligence Service documents state that CSIS provides security assessments to NATO concerning Canadians seeking sensitive positions abroad.Canada’s published personnel-clearance process also includes a law-enforcement inquiry conducted by the RCMP and an indices or loyalty check by CSIS.That process may also include credit checks, out-of-country verification and a security interview.CSIS cautions that its assessment is only one part of the process. The department, agency or organization sponsoring an applicant is ultimately responsible for granting, denying, suspending or revoking a clearance.The federal government has not disclosed who sponsored the woman’s clearance, when it was granted or what security level she held.It has also not said whether concerns about the suspect existed when she was screened or whether she may have been recruited or compromised after receiving clearance.Public Safety Minister Gary Anandasangaree said Monday that the allegations were “quite serious” and promised to examine how the woman gained access to NATO.“I think it’s important to get to the bottom of what happened,” he said during a news conference in New Westminster, B.C.“As a country, we will continue to investigate the processes we have and the security screening.”Anandasangaree said Canadian officials would also determine whether the suspect had previously performed work in Canada.Belgian prosecutors have not released her name, identified the country she allegedly served or disclosed what information she is accused of accessing or transmitting.NATO has said there is no indication that SHAPE’s operational readiness, command arrangements or ongoing work were adversely affected.The case nevertheless raises questions about how Canada screens citizens seeking access to sensitive positions inside allied institutions and whether existing clearances are reviewed after an individual begins working abroad.