China's ruling Communist Party on Saturday put up a strong defence of its much-criticised zero-COVID policy and ruled out its roll back, saying it is a "reality" that coronavirus is still lingering while describing Beijing's measures as the "most cost-effective".

Sun Yeli, spokesperson for the 20th National Congress of the Communist Party of China (CPC), said "China's measures to tackle the COVID-19 have worked well for the country and the zero-COVID policy is a science-based policy".

"COVID has dealt a heavy blow to economies all around the world. As things stand, however, it is still lingering, that is the reality", he said ahead of the once-in-a-five-year Congress which begins its weeklong session on Sunday.

Days ahead of the Congress, Beijing has witnessed rare public protests against President and Communist Party General Secretary Xi Jinping, denouncing the zero-COVID policy of periodic lockdowns of the cities with cases and strict control measures resulting in the slowdown of the economy and fuelling unemployment.

China, where the first case of the coronavirus was reported in December 2019 in Wuhan city, follows a "zero-Covid" strategy, including mass testing, strict isolation rules and local lockdowns.

China's measures to tackle the COVID-19 epidemic are the most cost-effective and have worked the best for the country, Sun said when asked if the measures which slowed down the economy will be relaxed.

"We give top priority to people's health and safety. This is part and parcel of our epidemic response efforts and the dynamic zero-COVID policy has been adopted in light of China's national realities and it is a science-based policy", Sun added.

"China has a big population including elderly people and the development is uneven among regions and medical resources are insufficient", he said.

On the whole, the dynamic zero-COVID policy has enabled us to keep infection and fatality rates at a very low level, he said, adding that the policy has worked best for the country.

He also played down concerns over the slowdown of the Chinese economy.

From 2013 to 2021 under President Xi's leadership, China's GDP has grown by 6.6 per cent annually, higher than the global average of 2.6 per cent and 3.7 per cent growth rate of other developing economies.

He said "China remains an important anchor of stability and a driving force of global economic growth".

"All things considered, China's development still has many favourable conditions", Sun said.

"The Chinese economy has strong resilience, great potential and robust vitality, and the fundamentals for its long-term positive growth remain unchanged," he said.

Downplaying the steady decline of the world's second-largest economy, Sun said "the speed of growth is not the only important yardstick".

"China is focusing on high-quality development", he added.