In a Facebook post published over the weekend, the Chinese embassy said such claims were “groundless smears and accusations”.

“The embassy would like to reiterate that China is firmly against and cracks down all forms of cyberattacks in accordance with law. China does not encourage, support or condone hacking activities,” it wrote on Saturday.

Last Friday, a Singaporean minister said the espionage group UNC3886 was “going after high value strategic threat targets, vital infrastructure that delivers essential services” but did not give details of the attacks.

The minister did not link the group to China but Google-owned cybersecurity firm Mandiant has described UNC3886 as a “China-nexus espionage group” that has attacked defence, technology and telecommunications organisations in the US and Asia.

Beijing routinely denies any allegations of cyberespionage, and says it opposes all forms of cyberattacks and is in fact a victim of such threats.

Singapore’s critical infrastructure sectors include energy, water, banking, finance, healthcare, transport, government, communication, media, as well as security and emergency services, according to the country’s cyber agency.