There will be major disruption to train services between Cambridge and Ely after a signalling fault at Waterbeach station.
A spokesman for Greater Anglia tweeted this morning (May 5): "Due to a fault with the signalling system between Ely and Cambridge all lines are blocked. Train services running through these stations may be cancelled or revised. Disruption is expected until 12pm.
"We are currently resourcing rail replacement transport to operate between Ely and Cambridge an estimated time of arrival will be given as soon as this information is available."
The disruption comes as strikes take place across the Greater Anglia network.
A 24-hour strike is to go ahead in the latest protest in a long-running dispute over train staffing levels.
The Rail, Maritime and Transport (RMT) union has confirmed the strike will go ahead on today, the same day as the iconic 2,000 Guineas race in Newmarket.
A further 24-hour walkout on Wednesday (May 9) is also planned.
The strikes are over a long-running dispute between train operators and staff over the role of conductors on trains.
Operators want to extend Driver-Only Operation (DOO) procedures across their networks, but union chiefs say this will affect passenger safety.