They complained the National Cyber Security Centre (NCSC) did not engage or show interest in investigating the episode, the second time in under a year the website of the campaign group of international parliamentarians had been knocked out.
Lee had been photographed meeting former prime minister David Cameron in 2015 and had given £584,177 to help fund the office of Labour MP and former shadow cabinet member Barry Gardiner.
Beijing has responded with hostility. Five British members of the group and several more from the EU have been sanctioned by Beijing for speaking out about the treatment of the Uyghur Muslim minority, including Loughton and Labour peer Helena Kennedy.
Last October, Ipac held a meeting on the margins of the G20 summit in Rome to protest against the presence of the Chinese foreign minister, Wang Yi, and urge leaders not to let China off the hook over human rights abuses in return for cooperation on the climate crisis.
China normally denies allegations of hacking or cyber interference, accusing the US and its allies of engaging in smear campaigns, although the topic is a subject of growing diplomatic and intelligence agency concern in the west.
