Passengers raised concerns, with one posting on social media that they saw a man boarded a tram at Queens Road wearing a gas mask.
The post stated the man got off at the very next stop and waved at the tram as it left the station.
It claimed that some people began to feel uncomfortable after this and left the tram.
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Transport for Greater Manchester has now confirmed they received the same reports and that they are currently assisting with police as they make enquiries.
A spokesperson for TfGM said: “We are aware of these incidents on Metrolink and are assisting Greater Manchester Police 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 Greater Manchester Police is of vital importance, and we’ll keep working together to continuously improve safety across the network.”
Greater Manchester Police has been approached for comment.
