A man told police he was selling 'crushed paracetamol' when he was spotted attempting to flog bags of white powder in Manchester city centre.
Cops said the powder was tested and was found to be cocaine.
Officers arrested a man at St Peter's Square tram stop.
The suspect allegedly told police it was an 'unlawful arrest'.
GMP's city centre division tweeted about the incident this evening (Saturday).
Police did not issue further details about the arrest.
The tweet, posted at at 7.15pm, read: "Male arrested at St Peters Square Metrolink stop after seen by officers trying to sell bags of white powder to to people.
"Tried saying it was crushed up paracetamol and told officers it was an unlawful arrest.
"Surprisingly it was tested and was... cocaine."
