There were reports of a 'smell of rotten chicken' in the town centre on Friday morning.
A businessman said he first caught a whiff of the unusual smell in Bolton last week but the stench had got worse today and he had reported it to the Environment Agency.
The man, who did not wish to be named, said: "Why does the town centre smell of rotten chicken?
“It is near where the new bus station is and down Thynne Street and Newport Street.
“It is horrendous. Last week when I was coming in to work I could smell it then but now it has got even worse.”
Bolton Council has been contacted.