Rishi Sunak has critcised the “naive” approach to dealing with China under previous Tory leaderships as he warned the “golden age” of Anglo-Chinese relations was over.

But the prime minister added “we cannot simply ignore China’s significance”, and said the UK needs to “evolve its approach” towards the country as he signalled closer “diplomacy and engagement” with the growing superpower.

The comments, amid growing popular unrest on the streets across China, will be interpreted as a dig at former chancellor George Osborne, who vowed to “make Britain China’s best partner in the West” and create a “golden decade”.

It comes as protests against China’s strict Covid lockdown measures have been billed as the biggest backlash against country’s authoritarian Communist Party since the 1980s.

As the country edges towards a fourth year of restrictions, thousands have flocked to Beijing, Shanghai and Wuhan streets calling for immediate change.

In Shanghai, there were angry clashes as the police cracked down on demonstrators, with a BBC journalist “beaten and kicked by the police”, according to the corporation.

In his first major foreign policy speech as PM at the annual Lord Mayor’s Banquet in London, Sunak said: “Let’s be clear, the so-called ‘golden era’ is over, along with the naïve idea that trade would lead to social and political reform. But nor should we rely on simplistic Cold War rhetoric.

“We recognise China poses a systemic challenge to our values and interests, a challenge that grows more acute as it moves towards even greater authoritarianism.

“Instead of listening to their people’s protests, the Chinese government has chosen to crack down further, including by assaulting a BBC journalist. The media – and our parliamentarians – must be able to highlight these issues without sanction, including calling out abuses in Xinjiang – and the curtailment of freedom in Hong Kong.”

He added: “Of course, we cannot simply ignore China’s significance in world affairs – to global economic stability or issues like climate change. The US, Canada, Australia, Japan and many others understand this too.

“So together we’ll manage this sharpening competition, including with diplomacy and engagement.”

The tone is in sharp contrast to Osborne in 2015, who brushed off the country’s human rights abuses during a charm offensive while giving a speech at the Shanghai Stock Exchange.

It came as it was announced that Chinese firms would help fund a new UK nuclear power station at Hinkley Point in Somerset.

Osborne said: “I believe our two countries are perfectly positioned to be partners in growth.

“Britain can be China’s best partner in the West. Of course, there will be ups and downs in the road ahead, but by sticking together we can make this a golden era for the UK-China relationship for many years to come.”

In his speech, Sunak also warned that “short-termism or wishful thinking will not suffice” in the face of threats from Russia and China.

The prime minister said: “We can’t depend on Cold War arguments or approaches, or mere sentimentality about our past.

“So, we will make an evolutionary leap in our approach.

“This means being stronger in defending our values and the openness on which our prosperity depends. It means delivering a stronger economy at home, as the foundation of our strength abroad.

“It means standing up to our competitors, not with grand rhetoric but with robust pragmatism.

“We will do all this not only through our diplomatic expertise, science and technology leadership, and investment in defence and security, but by dramatically increasing the quality and depth of our partnerships with like-minded allies around the world.”