China’s ambassador to the UK has accused the UK’s foreign secretary, Jeremy Hunt, of having a “cold war mentality” in his approach to the diplomatic row over Hong Kong.

Liu Xiaoming criticised the Conservative leadership candidate for his stance of “strategic ambiguity” on the possibility of sanctions against China over the crackdown on the ongoing protests in Hong Kong.

Last week Hunt stressed the UK’s “support for Hong Kong and its freedoms” after protesters broke into the territory’s legislative chamber on the 22nd anniversary of the handover of sovereignty from Britain to China. The protests are focused on a proposal to make it easier to extradite people to mainland China.

Liu said China was “not interested in diplomatic war with the UK” over the former colony. Speaking on BBC’s Andrew Marr Show, he said: “We are strongly opposed to British intervention in Hong Kong’s internal affairs.”

He continued: “We are still committed to this golden era between our two countries. But I cannot agree with some politicians’ description of the relationship, even the use of the so-called ‘strategic ambiguity’. This language does not belong to the vocabulary between China and the UK. It is cold war mentality language.”

Hunt, whose father fought in the navy during the cold war, had used the phrase when asked to set out what the diplomatic consequences of the row with Beijing might be.

“No foreign secretary would ever spell out precisely what would happen in a situation like that – you need what Bill Clinton called strategic ambiguity,” Hunt said.

Quick guide Democracy under fire in Hong Kong since 1997 Show Hide Hong Kong’s democratic struggles since 1997 1 July 1997: Hong Kong, previously a British colony, is returned to China under the framework of “one country, two systems”. The “Basic Law” constitution guarantees to protect, for the next 50 years, the democratic institutions that make Hong Kong distinct from Communist-ruled mainland China. 2003: Hong Kong’s leaders introduce legislation that would forbid acts of treason and subversion against the Chinese government. The bill resembles laws used to charge dissidents on the mainland. An estimated half a million people turn out to protest against the bill. As a result of the backlash, further action on the proposal is halted. 2007: The Basic Law stated that the ultimate aim was for Hong Kong’s voters to achieve a complete democracy, but China decides in 2007 that universal suffrage in elections for the chief executive cannot be implemented until 2017. Some lawmakers are chosen by business and trade groups, while others are elected by vote. In a bid to accelerate a decision on universal suffrage, five lawmakers resign. But this act is followed by the adoption of the Beijing-backed electoral changes, which expand the chief executive’s selection committee and add more seats for lawmakers elected by direct vote. The legislation divides Hong Kong's pro-democracy camp, as some support the reforms while others say they will only delay full democracy while reinforcing a structure that favors Beijing. 2014: The Chinese government introduces a bill allowing Hong Kong residents to vote for their leader in 2017, but with one major caveat: the candidates must be approved by Beijing. Pro-democracy lawmakers are incensed by the bill, which they call an example of “fake universal suffrage” and “fake democracy”. The move triggers a massive protest as crowds occupy some of Hong Kong’s most crowded districts for 70 days. In June 2015, Hong Kong legislators formally reject the bill, and electoral reform stalls. The current chief executive, Carrie Lam, widely seen as the Chinese Communist party’s favoured candidate, is hand-picked in 2017 by a 1,200-person committee dominated by pro-Beijing elites. 2019: Lam pushes amendments to extradition laws that would allow people to be sent to mainland China to face charges. The proposed legislation triggers a huge protest, with organisers putting the turnout at 1 million, and a standoff that forces the legislature to postpone debate on the bills. After weeks of protest, often meeting with violent reprisals from the Hong Kong police, Lam announced that she would withdraw the bill. Photograph: Dale de la Rey/AFP

The weeks of protests in Hong Kong have led to the territory’s leader, Carrie Lam, suspending the extradition bill and apologising for the way it was handled. Activists want it to be formally withdrawn and for her to quit. On Sunday protesters targeted transport links to the mainland.

Liu was summoned to the Foreign Office for a dressing down on 3 July, the same day he used a press conference to lambast the UK government for its comments on the Hong Kong protests.

Relations between London and Beijing have also been strained by the ongoing uncertainty over whether Huawei will be allowed to play a role in the UK’s 5G mobile infrastructure.

The US has been pushing for allies to block Huawei, claiming it could pose a security risk – allegations strenuously denied by Huawei.

Huawei is involved in building 5G networks in six of the seven cities in the UK where Vodafone’s service has gone live, even though the government has yet to confirm whether the company will be permitted to build the next generation of wireless infrastructure, the Observer reported on Saturday.

It is also helping build hundreds of 5G sites for EE and has won 5G contracts to build networks for Three and O2 when they go live.

Liu said he could give a guarantee that the firm would not pass secrets gleaned from the 5G network to Beijing. “I can promise that, 100%,” he said. “I think Huawei is a good company, it is a leader on 5G. I think if you reject Huawei you will miss enormous opportunities. They are here for win-win co-operation, they are not here to spy [on] people.”