Northern rail’s attempts to remove guards from trains in the north of England have been dealt a blow after the statutory body tasked with planning transport in the region publicly opposed the plans.

Transport for the North (TfN), which prioritises long-term infrastructure investment in the north, asked Northern Rail to return to the negotiating table with the Rail, Maritime and Transport union. The RMT has called strike action for 19 consecutive Saturdays, significantly disrupting rail travel across the north of England during the key Christmas period.

In a statement on Tuesday TfN said: “Transport for the North does not support removing the second person from trains, particularly when a significant proportion of rail stations in the north of England are classed as inaccessible for disabled passengers.”

Northern has refused to guarantee a guard on every train in future and instead wants to introduce driver-only operation (DOO). The RMT has long argued that guards are “safety-critical” and that their removal will only benefit the German state railway, which owns Northern.

But Northern insists it wants to keep a second person on “many” services. It says Britain’s most senior railway safety inspector says DOO is a safe way of working, and this way of running trains is in regular use across the network in the UK and abroad.

TfN urged the RMT to call off the strike, saying: “Transport for the North is concerned that the ongoing industrial dispute between Northern and the RMT, with further industrial action planned in the run-up to Christmas, will add to the significant disruption that rail passengers across the North of England continue to experience.”

The RMT general secretary, Mick Cash, said: “In light of the statement from Transport for the North, RMT awaits any new proposals from Northern rail which maintain for the travelling public the same level of safety, security and access that they enjoy at the moment based on the guarantee of the guard on every train. RMT remains available for talks.”

RMT strike action means a very limited service for many customers on Northern routes on Saturdays until the end of the year, with very few trains running after 5pm.

David Brown, the managing director at Northern, said: “This targeted action disrupts our customers’ lives. But, as we enter a vital period for businesses, it also damages the economic wellbeing of the north of England.”