Train services between Bruges and Ostend were suspended in both directions early on Tuesday after cables were stolen near Ostend station, rail infrastructure manager Infrabel said.
Repair work was underway on Tuesday morning, but the disruption was expected to last until at least midday, according to the SNCB/NMBS national rail operator.
The operator had initially hoped services would resume earlier in the morning.
However, the cables were cut in several places overnight, extending the time needed for repairs.
Replacement SNCB/NMBS buses were deployed for passengers.
Travellers can also use De Lijn trams between Ostend and Blankenberge.
