Speaking during a Transport for the North board meeting in Manchester on Tuesday, Ms Brabin said using Covid as a reason for running reduced services no longer stood up to scrutiny given Leeds station is now seeing pre-pandemic levels of passengers at weekends.
"We are having cuts under the smokescreen of Covid when in Leeds station at weekends we are at 110 per cent capacity pre-Covid," she said.
"The Government are making this argument that we are having to have these timetables because of Covid."
A report discussed by the TfN board warned that train operators are being asked to make "substantial savings" by Government.
The report said the subsidy received by rail operators from Government was £16.9bn in 2020/21 - a £10.4bn increase on the year before as funding was increased as a result of Covid measures decimating normal passenger numbers.
While rail demand has recovered more strongly in the North than in other parts of the country for the region's two main operators Northern and TransPennine Express, it is still below pre-pandemic levels. But services have also been cut, with the December 2021 timetable offering around 85 per cent of the services available before Covid.
Although some additional services, such as the restoration of a half-hourly service between Hull and Bridlington, are due to return from May, the report warns that this will have to be offset with savings from other areas such as marketing budgets.
The report said the financial position means further service cuts are likely in 2023.
"It isn’t clear that there will be sufficient funding to continue to support all services included in next year’s plan or to continue to growth back of services to pre-Covid levels," it said.
Greater Manchester mayor Andy Burnham said he was strongly opposed to further cuts to rail services and warned it would lead to a "car-led recovery" for the region, with people unable to use public transport to return to offices.
"We are going to be asked to accept a downgraded timetable from December 2022 and this is talking about further budget cuts coming on top of that," he said.
"To have any suggestion we are going to lose rail services from a reduced timetable - no way should we be asked to consider that."
Mr Burnham said he was also concerned about a reference to "workforce modernisation" as part of the savings plans - saying he was concerned that reducing staff numbers on trains would risk passenger safety.
"We went through that before with the attempt to remove guards from the train," he said.
"In my view, it just destroys public confidence in using the public transport system, particularly for women and girls.
"Guards on trains build public confidence in using the rail system. I'm very worried about what this means. What are we being threatened with here?
"It feels to me the plan is for managed decline of the railways in the post pandemic period and a car-led recovery. How is that going to work for the country in the long run? Surely we should be doing the opposite and encouraging people back to the office via the train. This seems to me to be a plan to do the exact opposite."
Ms Brabin said she was also concerned about the potential loss of staff from trains, as well as potential further cuts to services.
"I stood a manifesto of the safety of women and girls, and the idea that efficiencies are going to take away the safety in our stations for women travelling and vulnerable people travelling is something I will not countenance.
"It feels like from this report, it is managed decline. They are giving us the bare minimum to get from A to B it's just not acceptable."
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