Twenty-one trams were removed from service on Friday morning until further notice after the vehicle manufacturer identified cracks in the underframe structure at either end of the tram.
Inspections of the trams has started and will continue through the weekend and be completed by Monday, then Midland Metro will decide when to resume service.
Metro tickets and passes will be valid on some alternative modes of transport including some bus services, West Midlands Railway and Avanti train services.
Steve McAleavy, managing director Midland Metro Ltd, said: “Firstly I want to say how sorry we are for the inconvenience the suspension has caused to the many people who depend on West Midlands Metro services everyday.
“The Metro team have done an outstanding job during the pandemic to continue to deliver safe and reliable services, so it is a great disappointment that we have had to suspend services just when people are travelling more confidently.
“We have a fleet of CAF Urbos 3 trams and the manufacturer of those trams in a maintenance inspection identified some cracks in the underframe structure at either end of the tram. CAF were unable to assure us that the cracks did not represent a safety issue if we continued to operate.
“Our first priority is to ensure the safety of our customers and our colleagues and therefore the right thing to do was to remove the trams from service whilst inspections are carried out.
“The inspections have already commenced and will continue throughout the weekend and will be completed by Monday. Once the inspections have been completed we will be able to make a decision about when we can resume service.
“We will be keeping everyone updated via social media and will issue updates as we get more information.”
Eight new trams were brought in recently from Spain as part of a multi-million pound expansion of the network. Work has been ongoing in Wolverhampton city centre over recent years to extend the Metro line to the rebuilt train station.
A statement from West Midlands Metro earlier on Friday said: "Following maintenance checks, CAF, the manufacturer of the Urbos 3 trams used on the West Midlands Metro, has informed us of a fault affecting a small number of our trams. As a result of their findings, we have made the decision to remove the whole fleet from service to allow all trams to be inspected.
"At no point has customer or staff safety been compromised. This is a temporary and precautionary measure we have taken to ensure the service can continue to run safely and efficiently in the future. We are currently working alongside CAF to restore service as soon as possible.
"We are sorry for the inconvenience this will cause. Alternative services are detailed below and arrangements are in place to ensure our customers are still able to travel safely and reliably around the region.
"All Metro tickets will be valid on bus service 79 between Wolverhampton – West Bromwich and Birmingham. Passengers can also use train services between Birmingham Snow Hill, the Jewellery Quarter and The Hawthorns as well as train services between Wolverhampton and Birmingham New Street.
"The manufacturer has already started inspections on the fleet of trams and the Metro engineering team are working closely with them so that services can resume as quickly as possible. We will keep customers fully updated via our website and social media channels."
Find the latest information at westmidlandsmetro.com