OTTAWA - Failure rates for immigrants writing citizenship tests have soared since the spring, when tougher questions and revamped rules made it harder for newcomers to become Canadian.

The new test, introduced March 15, was based on a bulked-up citizenship guide released a year ago to give immigrants a richer picture of Canada's history, culture, law and politics.

The 63-page guide, Discover Canada, replaced a slimmer volume dating from 1995 that had fewer facts to memorize. The failure rate for the old citizenship test, with questions drawn from the smaller guide, ranged between four and eight per cent.

Failure rates for the new test, however, rocketed to about 30 per cent when it was first introduced -- prompting officials to revise the rules to avoid clogging the system with thousands of would-be Canadians who, because they had flunked, often had to plead their cases before busy citizenship judges.

A reworked test introduced Oct. 14 is helping to cut the national failure rate to about 20 per cent, still far higher than historic levels and making the exam-hall experience much more nerve-wracking for newcomers.

Hundred of documents outlining the bumpy introduction of the new tests were obtained by The Canadian Press under the Access to Information Act.

"This is the highest number of fails I have seen in my time here with CIC (Citizenship and Immigration Canada) doing the test," said a harried official at a Mississauga, Ont., office on March 19 this year, where 15 of 43 people had failed that day.

The old and new tests both have 20 multiple-choice questions and a 30-minute time limit. Only those citizenship wannabes aged 18 to 54 years are required to write the test, which is available in French and English.

But the pass mark for the test introduced March 15 was set at 75 per cent, meaning at least 15 of the 20 answers had to be correct. That compares with just 60 per cent, or 12 right answers, for the old exam.

The impact of the tough new standards was dramatic: shocked officials at testing centres across the country reported massive failure rates in the first sittings.

"I couldn't believe it, it's the highest fail rate I have ever seen here," one Toronto-area official reported by email to headquarters.

An internal survey of 35 testing centres across Canada, carried out between April 19 and June 24, showed an average of one in four people were flunking. At some centres -- such as the busy Etobicoke office in Toronto -- it was one in three.

And while many people under the previous regime finished the test within 15 minutes, the new exam had most people sweating for the full half hour.

People who failed the old test were automatically referred to a citizenship judge. In 2008-2009, for example, 9,500 applicants who blew the test had to spend up to an hour with a judge to argue they were still worthy of citizenship.

Worried that the tougher tests could swamp the system, officials decided that applicants who flunked would be allowed to rewrite. And in the revamped test introduced Oct. 14, the department further eased the rules by eliminating a long-standing policy requiring correct answers to a few mandatory questions.

"We anticipate that the pass rate will settle in the 80 per cent to 85 per cent range, which would indicate that the test is not too easy or too difficult," said department spokeswoman Karen Shadd.

She added that the test questions are being shuffled more often to help end what the department believes was rampant cheating under the old system.

"In the past, with the old test, some people would buy the answers from unofficial sources," Shadd said in an email.

"After paying for the answers, they would memorize them in order to pass the test. This accounted, in part, for a much higher pass rate."

Shadd also said the option of rewriting the test is only a temporary measure implemented to deal with the transition to the new exam.

She declined to provide an example of the test but said typical questions are either fact-based -- "Name two Canadian symbols" -- or conceptual, such as "What is the meaning of the Remembrance Day poppy?" Sample questions are included in Discover Canada.

The internal survey of 35 testing centres in late spring found the Etobicoke office in Toronto had the highest failure rate at 34.9 per cent, followed closely by Surrey, B.C. (33.7), Winnipeg (31.5), Scarborough in eastern Toronto (31.3) and Niagara Falls, Ont. (30.4). Officials declined to speculate on why these were the worst performers, but said education levels rather than mother tongue appear to be a big factor.

Citizenship and Immigration administers about 150,000 citizenship tests each year. The current 75 per cent pass mark is the same as in Australia and the United Kingdom, but higher than the 60 per cent set by the United States.

Shadd would not say how the new tests have increased the department's workload, only that "there were times of heavier than normal workloads during the most intensive monitoring phase when we initially implemented the new test."