According to the government's official policy, federal institutions must ensure that their communications conform to the Official Languages Act, Stephane Dion writes in a letter to Clement.
Dion, the Liberal official languages critic, said an overwhelming number of ministers — including Clement himself — do not do so on social media.
"You yourself, minister, fail to meet bilingual requirements in your electronic communications on government matters," Dion wrote. "And you are not alone in this. Many ministers use almost only English in their Twitter communications."
Dion listed 16 Conservative cabinet ministers who tend to tweet primarily in English. He added that International Development Minister Christian Paradis often fails to communicate in English in his online communications.
He says the tendency raises concerns that social media becomes a way to circumvent the requirements of the act.
"The bilingual requirement must fully extend to ministers' electronic communications," he wrote.
Dion's letter follows a scolding from the commissioner of official languages, who said federal ministers should be tweeting in both English and French.
Acting on a complaint, Graham Fraser concluded that former foreign affairs minister John Baird and Public Safety Minister Steven Blaney violated the language laws with unilingual tweets.
Fraser's office said cabinet ministers don't have to be bilingual, but when they communicate with the public in their official capacities, they must use both official languages.
Dion urged Clement, whose department is responsible for enforcing language policy, to correct the situation.
"He is the one who must ensure that everyone respects the Official Languages Act," Dion said in an interview. "It is difficult to achieve when he (Clement) himself does not do it."
Clement told Postmedia News last year that he'd prefer turning off his Twitter account rather than having to submit to language rules.
None of the Conservative ministers contacted last week were willing to comment on Fraser's preliminary conclusions.
Dion raised the matter Tuesday during question period, but was quickly shot down by Shelley Glover, the federal minister of heritage and official languages.
"What the member of the opposition has said is ridiculous. The government regularly communicates in both official languages," Glover said, noting the Twitter accounts in question were personal accounts.
"We take the two national languages of our country seriously."
One Conservative MP, Laurie Hawn, blasted Fraser's report last week, arguing that ministers should be allowed to express themselves in a language of their choice.
"Commissioner of Official Languages says cabinet ministers MUST tweet bilingual. Quelle idee stupide," Hawn wrote on his own Twitter account.
The Official Languages Act says parliamentarians can use one language in their private office and with staff.
They must, however, use both official languages when communicating "objectives, initiatives, decisions and measures taken or proposed by a ministry or the government,'' the report said.
The commissioner's investigation was prompted by several complaints.
The report states that during a two-month span, 181 of Baird's 202 tweets were English-only.
Blaney's Twitter account produced 31 tweets over two months and the vast majority were in both languages. Two were French-only and one was in English.
The report said parliamentarians should be communicating in both languages on all social media platforms, not just Twitter.
The commissioner declined an interview about the report because it is not yet public.
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