OTTAWA — The government says it needs to pump hundreds of millions of extra dollars into its student-loans program to keep the system functioning.

Budget documents tabled Tuesday show the Canada Student Loans Program needs an injection of $149.5 million to cover writeoffs of more than 60,000 unanticipated defaults.

At the same time, the program says it needs another $311.2 million to meet higher demand for the loans, just as repayments decline.

The request for extra funds comes just months after Ottawa scrambled to raise the ceiling on the amount of student-loan money it can have outstanding at any time.

The requirements for extra funding point to the mounting trouble students are having in paying rising tuition fees, says the Canadian Federation of Students.

"It's cause for concern," said David Molenhuis, the federation's chairperson.

Tuition fees have risen dramatically in the last few years, while students have been hit hard by the recession and find it increasingly difficult to save, he said.

"We've sounded several alarm bells."

It's not surprising that the government needs more money for the program, he said, because the delinquency rate for student borrowers rose to about 13 per cent in 2010-2011, compared with about 10 per cent a year earlier.

At the same time, the number of students borrowing money has risen 6.5 per cent in the last year, and the amount of money borrowed by students has jumped eight per cent.

"Certainly the majority of students require some form of debt repayment to fund their education," Molenhuis said.

"Without substantive changes, we're going to see higher levels of delinquencies."

A spokesman for Human Resources Minister Diane Finley, who oversees the program, said the loan defaults can be traced back seven years, and have nothing to do with today's tuition or the recession.

Ryan Sparrow said his government has been extra generous to students.

"As a result of the actions of our Conservative government, students now have access to more student grants than at any time in Canadian history."

Besides student loans, the government is seeking approval to spend an extra $1.8 billion beyond what was anticipated in earlier budget documents for the 2010-2011 fiscal year.

About half of that amount is for new initiatives, such as $216 million on a new National Defence headquarters. The other half is for increases in continuing federal programs, such as equalization and disability savings grants.

And some extra cash -- about $22 million -- is for the Canada Border Services Agency for costs associated with the arrival last August of the MV Sun Sea off British Columbia, with several hundred Tamil refugees.

Treasury Board President Stockwell Day says the government is well on its way to reaching its spending-control targets and eliminate the $45-billion deficit by the 2015-2016 fiscal year.

"We are on track and we are going to get there, and not by slashing programs to people," Day told a parliamentary committee on Tuesday.

In a testy exchange with opposition members during which MPs accused the minister of having no detailed plan, Day reiterated that he would balance the books mainly by freezing the operating budgets of government departments, and by ending the government stimulus program that has bloated government expenses for the past two years.

He lashed out at the parliamentary budget watchdog, Kevin Page, who has criticized the government for not putting forth a solid deficit-reduction plan.

"It is a factual inaccuracy to say there is no plan," Day said. "He is grossly wrong."

The Parliamentary Budget Officer has published an analysis of Day's operating budget freeze, concluding that the government has not thoroughly explained the impacts of its deficit-cutting exercise.

Day has said that much of the savings would come through attrition of public servants, but the PBO could not find much evidence of departmental planning to make do with far lower staffing levels.

"The fiscal objective is clear but there is no plan for Parliamentarians on how to achieve it," Page said in an email Tuesday, adding a long list of unanswered questions.

Day says he has left it up to deputy ministers to decide how best to make do with their budget freeze, and does not want to micro-manage their operations.