Showbiz
The Blue singer was photographed in the act and the evidence has been handed over to the police, the Sunday Mirror reports.
A police spokesperson said: "We do not condone this type of behaviour and this incident will be looked into."
Costa could be fined £100 if he is charged with a public order offence.
It was recently announced that Blue will represent the UK at this year's Eurovision Song Contest in Dusseldorf.
More: Antony Costa, Showbiz
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