All Metrolink tram services have been suspended while work continues to identify a communications fault.
The fault, which occurred at about 11.30am, means that the network control room staff are not able to monitor tram movements or access information displays.
The operator and contractors are currently working to identify the fault and no trams will run until further notice.
The Metrolink operator is also working with other operators to identify onward journey opportunities for passengers.
Anyone planning on using Metrolink is advised to use an alternative mode of transport, with arrangements being made for valid tickets and passes to be used on commercial bus services. Line by line information can be found on the Metrolink website – www.metrolink.co.uk.
Customers are advised to monitor the Metrolink and TfGM Twitter accounts or call customer relations staff on 0161 205 2000.
Metrolink Director, Peter Cushing, said: “All hands are to the pump and we are working a quickly as possible to identify and fix this fault.
“At the moment we are not clear on the cause and trams will not be operating until further notice.
“I’d like to apologise to all customers affected and want to reassure them that getting services up and running is our total priority alongside helping to get those currently onboard to their destination.”