The boss of Translink has warned the company could go out of existence unless it hikes fares or makes cuts to services.
David Strahan said that if radical action is not taken now, its future would come under threat within the next three years.
Earlier, MLAs were told the public transport operator faces "a very challenging" year ahead.
Around 150 workers could be laid off as part of a raft of cost-cutting measures, the Assembly's regional development committee heard. Translink announced in December that bus and rail fares would rise by 4%.
The price hike - which is more than three times the rate of inflation - took effect last month.
Senior officials from DRD and Translink faced criticism over the rise during yesterday's meeting.
Trevor Clarke, who chairs the committee, accused officials of making a "sneaky" announcement before Christmas.
He questioned whether it was an attempt to hide bad news when the media's focus was on the negotiations that led to the Stormont House Agreement.
Earlier Mr Strahan refused to rule out a further hike in fares in the coming year. Asked if he could guarantee prices wouldn't rise, he replied: "There is a balance to be struck in my view between increasing fares and cutting services.
"The position that we face, if we do not take action - Translink is not a sustainable organisation and it will not be here in the future.
"No one wants to see a fare increase, no one wants to see anyone lose their job - that's not why I joined Translink.
"However, the result of the funding reductions we're facing is that we have to take action.
"Ultimately it will be for the minister to decide where it falls in terms of fare increase vis-a-vis service optimisation."
Sinn Fein MLA Cathal O hOisin asked how quickly Translink could cease to be a going concern.
Mr Strahan replied: "The company is still a going concern but, if we don't take action now, at some point in my view in the next two to three years Translink will be flagged up as having going concern issues."
Yesterday it emerged Translink is considering rolling out a £10m voluntary exit scheme to help plug a £25m budget hole.
The plan was outlined in a briefing paper submitted to the DRD committee.
Ukip MLA David McNarry said: "It is a bit worrying and scary to read in the department's draft today of staff reductions, which could be 150 people costing £10m in redundancies."
Mr McNarry asked if the company was running at a loss, suggesting it was highly irregular and potentially illegal to allow such a practice.
DRD official Ciaran Doran replied: "I am certainly agreeing that it is running a loss this year and is projected to run a loss next year.
"I wouldn't agree that it is not complying with company law or meeting its legal or regulatory requirements," he added.
Victoria Stewart (20) Magherafelt Working student
“I pay £44.50 for 10 journeys from Toomebridge and last week it went up 50p. It’s unfair because I’m a student and I work too so I have to travel to Coleraine by bus as well a few days a week. It’s a lot considering you can get the train to Dublin for £8. I think the train would be better but it’s too far from my house to get one.”
Derek Bradley (71) Newry Pensioner
“I’m not too bad because it’s free for me but I think if I was paying for it, it would be too much. It’s dear enough and I feel bad for the young ones who are having a hard enough time just finding jobs and they’re having to pay bus fares. I get the Newry to Belfast and it’s always full so they’re doing well enough without putting the fares up.”
Bronagh Duggan (20) Castlewellan Student
“I only have to use the bus about once every two weeks to go home because I live up at university, at Jordanstown. It’s not really that bad because I don’t have to use the bus too much and I’m not sure of the fare but I think it’s under £5 for both ways. I don’t think the increase has been too much because I haven’t noticed it.”
Emma White (34) Lisburn Dental Technician
“I use the bus regularly from Lisburn to Belfast and I pay £135 which is unlimited so I can use it anytime at all and it includes the weekend as well. I think it is quite good value and it only went up £5 just recently. I would continue to use the bus because to drive it would be too expensive to pay for parking and for petrol as well.”
Kelly Morrison (20) Templepatrick Student
“I have to drive to Mossley or Antrim and then get the bus from there, and I use a Smartlink card which I pay £80 for 40 journeys. I just top it up but I haven’t topped it up yet so I’m not sure how much it will increase by yet. There is no train close enough for me to use so I’m pretty dependent on the bus and it’s expensive enough.”