Trains are currently unable to call at Kettering after a power cut in the area caused signalling problems.
No trains can run through the line in either direction after the line was closed this morning (Friday).
A statement from East Midlands Trains said: “At present Network Rail teams are going to investigate the problem, we will have more information shortly.
“Our trains are likely to experience extended delays or alterations. Trains are also extremely busy.
“You should use alternative routes which remain the most comfortable and quickest journey options.
“These arrangements will remain in place until the line re-opens and the train service recovers.”
Western Power Distribution says it hopes to restore all supplies by midday.