British police have previously charged three Russians, who they say are GRU military intelligence officers, with the 2018 attempt to murder former double agent Sergei Skripal with the military-grade nerve agent Novichok.

Secureworks - an arm of Dell Technologies' - says that Chinese spies are upping their game in response to 'likely increased pressure from (Chinese) leadership to avoid public scrutiny of its cyberespionage activity.'

Australian police allege that Alexander Csergo sold information to two Chinese spies known as 'Ken' and 'Evelyn' while he worked in Shanghai as a marketing executive.

David Ballantyne Smith, who has pleaded guilty to eight charges, is alleged to have collected information from as early as March 2018 until his arrest in August 2021.

Alireza Akbari, who was arrested more than two years ago, is said to have been a spy for Britain's MI6 secret intelligence agency and had received around US$2 million for his services.

The case focused on Ahmad Abouammo's efforts to look up information on two Twitter users, a US$42,000 watch he received from a Saudi official and a pair of US$100,000 wire transfers.

China is unlikely to display its best tactics and strategies during drills that it knows are being watched closely, said one of the officials, speaking on condition of anonymity.

Australian Prime Minister Scott Morrison has said it is 'absolutely untrue' Yang had been a spy for Australia.