ABOUT 5000 V/Line customers on the Ballarat train line had their service disrupted after vandals cut signal cables at Rockbank late last night.

Morning trains were delayed by up to 70 minutes and five services between Ballarat and Melbourne were cancelled.

The cables were cut in two places near Rockbank at 7.00pm causing disruptions for up to 5000 customers, according to V/Line. 

V/Line cancelled three services from Southern Cross - the 6:12am to Ballarat, the 7:12am to Bacchus Marsh and the 9:06am to Wendouree.

The 8:16am and 8:38am service from Bacchus Marsh to Melbourne have been cancelled, as has the 11:04am train from Wendouree to Melbourne.   

V/Line spokesperson Colin Tyrus said trains were “crawling” through Rockbank due to the loss of signal.

“When you lose signals have to run trains through caution at slow speed,” he said.

Mr Tyrus said because trains were running slowly, V/Line had to take some services out of the system to keep the timetable in order.

V/Line was repairing the damage, which delayed some trains by half an hour last night, and expected it to be completed by midday, he said.

“No one wants to start their Monday with these types of delays,” he said.  

“This senseless vandalism is frustrating to both our customers and V/Line.

“We want to remind people that damaging railway equipment is a criminal act and we urge anybody who knows anything about this vandalism to call Crime Stoppers.”  

V/Line repaired the damage before 2pm and normal service resumed shortly after.

"No one wants to start their Monday with these types of delays," Mr Tyrus said.

"This senseless vandalism is frustrating to both our customers and V/Line.

"We want to remind people that damaging railway equipment is a criminal act and we urge anybody who knows anything about this vandalism to call Crime Stoppers."

V/Line Chief Executive Theo Taifalos said: "Who in their right mind would cut a live cable right beside a rail track. It could cost the life of one of these fools."

Crime Stoppers can be contacted on 1800 333 000.