A man was allegedly letting gas off on trams on the Bury to Victoria line of the tram network.
Several people reported feeling discomfort or dizziness but no serious injuries have been reported.
Officers from Greater Manchester Police (GMP) have arrested a man on suspicion of possessing a noxious substance with intent to injure.
He remains in police custody for questioning today, Monday.
Police say that there is not believed to be any wider threat to the public and an investigation into the circumstances of the incidents are underway.
Anyone who believes they may have witnessed something suspicious is urged to get in touch with police.
READ NEXT: Police attend concern for welfare near tram stop
READ NEXT: Man diagnosed with terminal cancer using time to help
Detective Chief Inspector Paddy Connell, from GMP’s City of Manchester Division, said: “We fully appreciate that incidents of this nature can cause concern in our communities, but I want to reassure the public that we do not believe there is any wider threat present.
“We have now secured the arrest of a man and are working hard to establish the full circumstances of the events that have been reported over recent days.
“As officers continue to work their way through all the evidence available, we are asking anyone who has any information to please come forward.
“This includes anyone who believes they have witnessed something suspicious, or similar to the incidents that we are dealing with.
“Our transport hubs are operating as usual, and I would encourage anyone with any concerns to speak to a police officer, who will be more than happy to discuss any queries you may have.”
On Sunday, a spokesperson for Transport for Greater Manchester said: “We are aware of these incidents on Metrolink and are assisting GMP with their enquiries at this time.
“The safety of our passengers and staff is a core priority – everyone has the right to feel safe and be safe across the Bee Network.
“Through the TravelSafe partnership our close working relationship with GMP is of vital importance, and we’ll keep working together to continuously improve safety across the network.”
You can contact police via 101 or Live Chat service on the GMP website.
Alternatively, you can call the independent charity Crimestoppers, anonymously, on 0800 555 111.
