With Canadians facing a deadline today to complete their census questionnaires, former Conservative MP Dean Del Mastro is raising concerns about the personal questions on the long-form version of the survey.

Del Mastro posted a message on Facebook Tuesday saying he believes some of the queries in the long-form census may even violate Canadians’ constitutional right to privacy.

“Last week a long-form census was dropped at my door,” he wrote. “It’s 36 pages long and asks a significant number of questions that I don't feel government has a right to demand under penalty.”

The deadline for completing census forms comes at midnight on May 10, including the mandatory long-form that was resurrected by the Liberal government after the Conservatives replaced it -- controversially -- with a voluntary survey in 2011.

Del Mastro said he was concerned to learn that, instead of asking questions about the respondents’ income on the long-form, Statistics Canada is receiving this data directly from the Canada Revenue Agency.

“We should demonstrate real concerns around how this kind of information is passed around, even within government,” he told CTV News.

He says the sensitive personal data could be obtained by hackers and notes high-profile cases of government data leaks, including a breach of the House of Commons computers last year.

Statistics Canada says it is allowed by law to obtain tax records for research purposes and notes that the data are kept strictly confidential.

“Census data are processed and stored on a highly-restricted internal network and cannot be accessed by anyone who is not a deemed Statistics Canada employee,” the agency said in a written statement.

Del Mastro also said he doesn’t think Canadians should be forced to answer questions about family members’ mental health or sexual orientation on the long-form version, which is sent to one in four households.

The long-form questionnaire asks how often people in the household experience “emotional, psychological or mental health conditions (e.g., anxiety, depression, bipolar disorder, substance abuse, anorexia, etc.)?”

It contains questions about relationship status and specifically whether people in the household live in same-sex marriages or common-law relationships.

“Some people aren’t prepared to answer those personal questions about their life,” Del Mastro said. “Either they’re going to lie or they should have the option to not answer it all.”

He says he understands that government wants as much data as it can get but cautions, “These desires need to be balanced against personal privacy.”

The former Peterborough, Ont., MP, who once served as then-prime minister Stephen Harper’s parliamentary secretary, is currently free on bail pending a second stage of appeal of his conviction for breaking campaign finance rules in the 2008 election.

Del Mastro doesn’t go so far as to suggest Canadians refuse to respond the survey, however, and says he will comply but thinks people should have the right to say no to some of the questions.

The census is also targeted by an online campaign, CountMeOut.ca, that encourages “minimum co-operation” to make it more difficult for Statistics Canada to collect the data. It suggests refusing to fill out the census online and instead requesting the large-print version. It also hints that spilling coffee on the form, cutting the form with scissors and applying kids’ stickers over its barcode are techniques that could complicate scanning the forms.

So far, Statistic Canada says it has received census responses from 5.7 million households, describing this as “strong initial support.” According to the 2011 census, there were 13.3 million households in Canada.

Those who miss filing by midnight Tuesday will get reminders from Statistic Canada and, eventually, visits from enumerators.

Technically, refusal to complete the forms could result in a maximum penalty of a $500 fine and three months in jail, though no one has ever been incarcerated for not completing the census.