The British foreign secretary and aspirant prime minister Jeremy Hunt threatened China with “serious consequences” over its treatment of protesters in Hong Kong.

Hunt refused to rule-out sanctions against the world’s second-biggest economy. Trying to avoid a self-fulfilling prophecy, Hunt told the BBC that the UK would not just “gulp and move on” if China cracks down on protesters.

The UK claims a right to intervene on the basis of its bilateral agreement with China in 1984, which handed the 150-year old colony to China. Leaving Hong Kong in 1997, the UK had secured an agreement that Hong Kong would continue to enjoy a degree of economic autonomy and individual liberties that is unlike mainland China. Since 1997, when Hong Kong was surrendered to China, the former colony has been ruled under the “one country, two systems” principle.

In view of the recent crackdown on protestors, China’s ambassador to London was summoned to the Foreign Office on Wednesday. Ambassador Liu Xiaoming said relations between China and the UK have been damaged by Hunt’s comments, condemning the waving of the colonial British flag by protestors who stormed the Legislative Council. He recalled that under British rule there was neither a democracy nor a right to protest.