The government was warned two years ago there were not enough bus drivers to service its proposed new network, but kept its "head in the sand" and refused to hire more, the Transport Workers Union says.
Thousands of weekend bus services have been cancelled since the network overhaul in late April because bus drivers have not been available, with the union expecting the cancellations to last up to a year.
Transport Minister Chris Steel on Thursday said the government did not hire extra drivers before the new network rolled out because it didn't know how many drivers would make themselves available for the weekend services.
"We now know there are reliability issues particularly in the afternoons and evenings and we'll be recruiting more bus drivers to deliver those services," Mr Steel said.
He could not put a number on how many extra bus drivers would be required to service the network.
Transport Workers Union ACT branch secretary Klaus Pinkus said the suggestion that drivers not putting their hands up to work weekends was the reason for the cancellations was "a straight-out lie".
"People are working more weekends than they did before," he said.
"You could get them all working a maximum amount of weekends possible and you still wouldn't cover it. It's a workforce issue."
He said the government had kept its head in the sand for years about the need for more drivers.
"What they're doing now is what they should have been doing a year ago," Mr Pinkus said.
"Two years ago when they first suggested [the new network] we said they didn't have the workforce to do it."
Under the enterprise agreement, bus drivers are not forced to work weekends, instead there is a requirement to work a "reasonable number" of weekend shifts.
If they choose to work weekends, they are paid the same as if it were a weekday.
Opposition spokeswoman for transport Candice Burch said the government should consider paying drivers penalty rates on weekends, saying simply recruiting more drivers would not solve the problem.
She also called on the government to make weekend travel free until the service was fixed.
"The government really should have seen this coming before they promised all these weekday services under the new network," she said.
Miss Burch critisised Mr Steel for not releasing a list of bus services that will not run as scheduled when asked to in Question Time on Thursday.
He instead said people could check the NXTBUS app 90 minutes before their journey.