UPDATED 10.13am Christchurch residents are being urged to call the Fire Service or Environment Canterbury if they smell gas.

A number of complaints have been lodged across the city this morning about the worrying smell.

Bromley School remains shut today after becoming concerned by the smell yesterday.

It's thought the toxic smell could be coming from contractors turning over compost in Maces Road.

A number of callers told Newstalk ZB's Chris Lynch the smell hasn't gone away overnight.

"It's that type of gas it get's in the back of your throat as well I have rung ECan and the council they just said that it's not toxic. Well I said, how would you know if it was toxic or not," one caller said.

Another called in and said: "That smell yesterday was very very strong and it reminded me of a ruptured gas main. It sort of scared me a wee bit because it was so intense."

Fire communications shift manager Riwai Grace said "ECan are getting their people onto it as well, I think if people do notice anything strange ring 111, ring ECan, and the more people that report it the better, because then we can create a picture of where the smell is coming from."

ECan can be contacted on (03) 353-9007.