OTTAWA - Parliament's budget watchdog says Ottawa's extension of income support for unemployed workers during the COVID-19 pandemic will tack on more than $5 billion in government spending costs.

The government announced last month it would add 12 weeks of eligibility to the $500-a-week Canada Recovery Benefit in an attempt to get ahead of a looming panic around pandemic relief.

Parliamentary budget officer Yves Giroux says the move will cost an additional $5.2 billion, nudging the total price of the program to $50 billion.

He also says the government's three-month extension of aid for parents who must stay home with children because of the virus will add an extra $470 million in spending in the coming fiscal year, boosting total expenditures on the caregiver benefit to $3.3 billion.

Giroux projects a further $235 million will be spent on the $500-per-week sickness benefit after it was expanded to four weeks from two so workers can stay home if they're feeling ill or have to isolate due to COVID-19.

Labour groups have asked the Liberals to extend benefits until the end of the year, which is how long they believe it might take before the workers in hardest-hit industries get back on the job.