The head of the World Health Organization says China's "zero-COVID" policy is not sustainable, and the country should transition to another strategy.

The Chinese government maintains a zero-tolerance policy against the coronavirus, and aims to completely contain new infections. Lockdowns are being imposed in many areas of Shanghai, where infections are spreading.

WHO Director-General Tedros Adhanom Ghebreyesus said on Tuesday that the virus is evolving and becoming more transmissible. He said, "Changing measures will be very important."

He said the UN agency has discussed the issue with Chinese experts.

The head of the WHO's health emergencies program, Mike Ryan, indicated that government measures should show due respect to human rights and people's livelihoods.

Ryan said the WHO needs to "balance the control measures against the impact they have on society" and the economy.

It is rare for the WHO to comment on a particular government's coronavirus policy.