Residents have been told to evacuate around a road in the Christchurch suburb of Burnside after a “high-risk explosive substance” was found.

Senior Sergeant Craig Ellison said police were called to the scene in the vicinity of Sheffield Cres about 2.20pm.

“Police were alerted to a concerning substance,” he said.

People are asked to avoid the area and an increased police presence is in place while the substance is removed.

“Cordons will be removed once the area is safe,” Ellison said.

Burnside residents received an emergency alert advising them to “immediately evacuate” around Sheffield Cres because of a “high-risk explosive substance”.

Burnside residents have been told to evacuate after a "high-risk explosive" was found. Photo / Supplied