Two CFIA staffers got sick a day after taking nasal and blood samples from pigs in a barn on this central Alberta farm. (CBC)

The Canadian Food Inspection Agency tried to withhold specific details about a commercial flight taken by an inspector who was infected with swine flu and was carrying samples of the virus, CBC News has learned.

In July 2009, a CBC News investigation found that improperly trained and ill-equipped inspectors were infected with the virus in April that year, after investigating a quarantined farm in Alberta.

After exposure, one of the infected inspectors took a commercial flight to hand-deliver samples from the Alberta farm to the federal virology lab in Winnipeg.

Email correspondence released this week by the CFIA show the agency did not want to release details about the commercial flight the inspector took — an Air Canada Jazz flight that left Calgary on the morning of April 29.

However, the emails show the office of the agriculture minister intervened, and reversed the CFIA's decision to keep the flight details from being disclosed publicly. The details were then released.

In an email dated July 22, Bryan Blom, senior communications adviser for the CFIA, wrote: "MinO has asked us to provide the flight information in the name of transparency."

The CFIA's associate vice-president of operations, Catherine Airth, wrote: "I find the statement regarding flight info to be a bit brusque, but I guess we can't help it."

The ministry's decision to release the details came after the CBC filed a request under the Access to Information Act .

The request was filed after Dr. Jim Clark, the agency's national manager for disease control, refused on July 21 to provide the information, saying it wasn't relevant. He also argued a news agency like the CBC wasn't in a position to make a judgment about whether the individual posed a risk to other passengers on the plane.

Other email correspondence reveal that all the CFIA's written responses to CBC News were subject to approvals by both the Privy Council Office, an arm of the Prime Minister's Office, and the agriculture minister's office.

The emails suggest government officials were sensitive about the content of written responses to followup questions about the flight posed by CBC News. On July 24, the CFIA's Ingrid Nielsen wrote: "We've already answered these questions to the best of our ability. Now we stand down, and tweaking won't help. It will only antagonize [CBC] further."

Many portions of the emails are blacked out, deleting either the substance of the correspondence or the sender and receiver.

The release of the emails was delayed as a result of a backlog, the CFIA said. The release of more records to CBC News is still pending, including a request for more information on the two health inspectors who visited the farm.