Asbestos piping has been found buried at the QEII Stadium demolition site in Christchurch.
The Canterbury Earthquake Recovery Authority (CERA) said while some asbestos was noted in the original plans, and addressed in the demolition, the discovery was unexpected.
The small amount of piping was in the form of broken pipe pieces, and may have been offcuts of the original pipes buried when the complex was built in the 1970s.
Some areas of the site near the piping, including a public walking track, will be closed as a precaution to allow environmental testing.
This is to ensure no potentially affected debris has been inadvertently moved, and if so, can be contained, CERA said.
Results of the testing will be known next week.