Christchurch residents have reported a strong smell of smoke drifting across parts of the city, but Fire and Emergency says it is more than likely the result of a controlled burn.

Reports have come in from suburbs including Halswell and Waltham, with people noticing the distinct smell on Tuesday morning.

A teacher in Waltham said they made a decision to keep students inside the classroom because of the strong smell of smoke.

Fire Communications shift manager Lyn Crosson told Chris Lynch Media that crews from Spreydon had investigated areas around the Port Hills but had found no sign of any uncontrolled fire activity.

She said the combination of fog and cooler morning conditions may be causing the smoke to linger at low levels.

“Sometimes smoke can sit below the fog layer, which could be what residents are noticing,” Crosson said.

While no emergency fire has been located, Fire and Emergency said it will continue to monitor the situation.

It is also now an open fire season in Canterbury.