Stormont sources have criticised the decision of Infrastructure Minister Nichola Mallon not to propose furloughing Translink staff and have claimed it could have saved Northern Ireland up to £30m.
However, the department has strongly defended its actions and stressed that furloughing public sector workers would be a "hugely significant step" which would need to be seriously considered by the Executive in consultation with unions.
It also rejected the suggested savings of £30m as "a dangerous fantasy".
Ms Mallon was asked by Finance Minister Conor Murphy last month to consider if furloughing would be applicable to Translink, which runs Northern Ireland's public transport.
The company has been beset by financial difficulties which have been compounded by the coronavirus lockdown.
Chief executive Chris Conway has said it needs a £100m funding injection to continue providing a public transport network following a 90% drop in passenger numbers.
Speaking after raising the issue in the Assembly, DUP MLA Keith Buchanan noted that Transport for London had decided to furlough staff and asked why Ms Mallon "does not appear to have been more proactive in assessing this option".
Stormont sources claimed that furloughing Translink staff could have saved Northern Ireland £25-30m.
A Department of Infrastructure spokeswoman said that, following a Finance Department request, Ms Mallon asked officials to explore the feasibility and "benefits and risks" of furloughing non-essential Translink staff.
She said: "However, the minister has made clear her concerns that furloughing public sector workers is a hugely significant step which needs serious consideration by the Executive and in consultation with the trade unions. While consideration of the feasibility of furloughing is ongoing, the suggested savings of £30m has no basis in reality.
"It would involve closing the entire organisation for three months and removing all public transport. This is a dangerous fantasy which does a disservice to the contribution which Translink staff as key workers have been making on all our behalf at this time."
She added: "Our public sector workers at Translink are working to keep our public transport network operating through this difficult period to transport our Health and Social Care and other key workers to work and services.
"Indeed, any reduction in the current level of services could significantly undermine the Executive's strategy for managing Covid-19, impacting on our ability to support key workers and maintain social distancing on our public transport network."
Meanwhile, Conor Murphy has expressed concern that ending the Government's furlough scheme for workers in June will be too soon. Chancellor Rishi Sunak is reportedly exploring how to wind down the scheme.
Speaking at the daily Executive coronavirus press briefing, Mr Murphy said that even after lockdown restrictions were lifted, many businesses would struggle to return to pre-pandemic levels of operation. He called for analysis to be done around which sectors can and have returned to work.
The Finance Minister said it would be difficult for the Executive to take over the scheme as they don't have access to the HMRC database. He also acknowledged it would be "hugely costly" and pledged to make the case to the Treasury for businesses that are struggling to return to work.