Replacement trains have been sent out into service after three trains on the Metro system experienced faults.
Passengers using the network have been warned of wider impact on the timetable after two trains running between South Shields and St James have developed faults, while one on the line between Airport and South Hylton also has a fault.
A spokesman for the service said: "Apologies for any inconvenience whilst we get replacement trains in service from the depot.
"This will have a knock on effect as we will be using some peak service trains that usually run between Pelaw and Monkseaton and Regent Centre as the replacements, so trains will be busier on your journey to work this morning.
"Apologies and please leave plenty time for your journey."
It has issued an update saying trains running between St James and South Shields in both directions and Airport and South Hylton, also in both directions, are now all in service, with minor delays.
It added: "There are still six peak service trains that run between Pelaw and Monkseaton and Regent Centre not running due to faults."
Updates will be issued via the Metro's Facebook page and its Twitter account @My_Metro.