Plans for new train services between London and Wrexham, Rochdale and Blackpool have been rejected by the Office of Rail and Road (ORR).
The proposal to add more trains on the West Coast Main Line would “likely increase delays and cancelled trains for passengers”, the regulator said.
It rejected Wrexham, Shropshire and Midlands Railway’s application for four daily Wrexham to London Euston return services, as well as Lumo’s proposal for up to four return services between Rochdale and Euston on weekdays and Saturdays, and three on Sundays.
Avanti West Coast’s plans for additional services between Blackpool and Euston were also denied by the ORR.
The regulator said: “Gaps in the current timetable need to provide important space for trains to recover when disruption occurs, minimising delays to passengers.
“ORR concluded that adding more services into these windows in the timetable for recovery would reduce that resilience, increasing the risk of disruption spreading to other services and affecting more passengers.”