Labor has called on the home affairs minister, Peter Dutton, to explain whether a staff member in his office leaked national security information critical of the now-defunct medevac legislation.

While parliament was debating the medevac bill in February, the Australian’s Simon Benson reported a classified ministerial briefing from Asio and Border Force which warned that the bill to facilitate the transfer of refugees from Manus Island and Nauru for medical treatment would “undermine regional processing” and “compromise Australia’s strong border protection regime”.

The home affairs department referred the case to the AFP, but ultimately the AFP dropped the investigation, saying more than 200 people had access to parts of the document.

However, a Guardian Australia freedom of information request revealed only 11 people had access to the initial classified document.

In questions on notice to the Senate’s press freedom inquiry, published on Wednesday, the AFP confirmed email logs revealed only one person with a department email had contacted Benson during the period the document was suspected to have been leaked – a staff member in Dutton’s office.

But the AFP said that staff member had been ruled out of contention due to “additional information” provided by the department.

“The additional information provided by the department indicated the person who had contacted Simon Benson did not have access to the leaked material,” the AFP said. “The AFP cross-checked the individual against the list of people with access to the leaked information and they were not on that list.”

However, the AFP admitted it did not see the emails between Benson and the staff member, only the titles of the emails, and those did not relate to the leaked document.

Additionally, the AFP said it was not sure whether the staff member was on one of the email distribution lists that received the ministerial submission document. “That number is unknown as the email addresses provided do not stipulate if the member was working in the minister’s office.”

The shadow home affairs minister, Kristina Keneally, has suggested Dutton should order his staff member to hand over the emails to the AFP for investigation.

“When classified information that embarrassed the third-term Liberal National government ended up in the newspapers, the personal homes of journalists were raided,” she said.

“When classified national security information that suited the government’s political purposes ended up on the front pages of newspapers, the one person in touch with the relevant journalist hasn’t even been spoken to by police.

“Why is there always one standard for Peter Dutton and another for everyone else?”

Guardian Australia has sought comment from Dutton’s office.

Before the medevac legislation was repealed last month, a number of leaks of personal medical information of those transferred under the program were published in News Corp papers.

In one instance, the home affairs department referred the story – which contained information about a refugee transferred to Taiwan for medical treatment – to the AFP for investigation.

Ahead of the release of documents obtained under FOI, the department then claimed that the referral was made in error but declined to reveal how the information was provided to the Courier-Mail.