Chinese hackers with ties to Beijing gained unauthorised access to the email accounts of high-ranking US government officials, including the US Ambassador to China, Nicholas Burns.
The hackers also accessed the email account of Daniel Kritenbrink, the assistant secretary of State for East Asia, according to the Wall Street Journal.
The cyber-espionage attack is believed to have exposed a significant number of sensitive US government emails.
The breach has raised concerns about the security of diplomatic communications and potential implications for US-China relations.
The incident adds to the fallout from the alleged Chinese hack, which was first reported last week and also targeted the email accounts of other officials, including Commerce Secretary Gina Raimondo.
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