Video footage of the incident showed the protester, an 18-year-old man, attempting to strike the police officer with a stick, before being shot in the chest and collapsing to the ground. He underwent lung surgery and was in a non-life threatening condition, according to a source.

A Hong Kong police force spokeswoman said in a video posted to the force’s Facebook page that the officer had feared for his safety and had acted to “save his own life and his colleagues’ lives”.

Calling on both anti-government protesters and Hong Kong authorities to de-escalate the conflict, Raab said the incident “underlines the need for a constructive dialogue to address the legitimate concerns of the people of Hong Kong”.

Speaking to reporters on Tuesday after the shooting, EU spokeswoman Maja Kocijancic said the bloc “continues to stress that that dialogue, de-escalation and restraint are the only way forward”.

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“More than three months since the protests began, the right to assembly and the right to protest peacefully must continue to be upheld in line with the [Hong Kong] Basic Law and international commitments,” Kocijancic said.

Tuesday’s incident, which occurred during a day of demonstrations billed by protesters as an act of “national mourning”, cast a shadow over mainland celebrations of the anniversary of China’s founding in 1949.

Hong Kong’s embattled leader, Carrie Lam Cheng Yuet-ngor, faced criticism from pan-democratic lawmakers in Hong Kong for attending the Beijing festivities, which featured a military parade with thousands of troops and a flaunting of China’s latest advanced weaponry.

In Tiananmen Square, President Xi Jinping said in a speech that no force could “shake the status of our great motherland”.

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Lam’s appearance at the parade, which was also attended by several Hong Kong police officers, was “tantamount to authorising police to administer Hong Kong”, two dozen Hong Kong legislators said in a joint statement.

“The members of the democratic camp urge Lam to stop pretending to be communicating [with the public, and to stop] relying on police violence,” the statement said. “She must face the problems and respond to protesters’ five demands.”

Last week, Lam met with more than 130 Hongkongers in a town hall-style event, at which she came under fire over her handling of unrest in the city, including her ongoing refusal to approve an independent inquiry into allegations of police brutality.

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Lam offered few new commitments at the event, but vowed that detained protesters would no longer be sent to the San Uk Ling detention centre, where those held in custody have allegedly been maltreated.

Speaking on Tuesday, the EU’s Kocijancic said that while “initial positive steps to engage members of the public and various sectors of society in dialogue have been taken, further efforts are needed to restore trust”.

Additional reporting by AFP