Christchurch residents are reporting a foul odour in the city.

Social media users have described the smell as "like poos" or like "wet dog", with some Twitter users adding the hashtag reference #chchsmells.

Ruby Sanderson tweeted, "Why does Christchurch smell like dog poop today?".

Sean Hogan said, "So I'm not the only one smelling poo in Christchurch. Thought it was me."

Press Facebook users said the smell was like "wet dog", "fertiliser", "compost" and "vomity" and some said they first noticed it yesterday afternoon.

One poster joked that Bunnings at Tower Junction had been "full of mothers sniffing their babies bums".

Another, who noticed the smell in the central city last night, said the strong odour had made a colleague dry-retch.

Residents in Avonhead, Ilam, Addington, Russley Somerfield, Opawa, Westmorland and Beckenham have all reported the smell.

However, people in Christchurch's eastern suburbs, including those near Woolston's strong-smelling Gelita gelatine plant, are reporting no noticeable smell.

The source of the smell remains unknown.

A representative from Christchurch City Council was unsure of the smell's origin.

Environment Canterbury were not able to be reached by Press reporters.

Can you smell the offensive odour? Do you know where it's coming from? Comment below.