A group consisting of more than 50 politicians, including former Tory leader Iain Duncan Smith, have written to HSBC Chairman Mark Tucker demanding he unfreeze the accounts of Hui and his family, according to the report.

In their letter, seen by The Times, members of the Inter-Parliamentary Alliance on China say it is “highly concerning” that the accounts of Hui’s family members are frozen, even though they are not subject to any charges.

They also warn that HSBC has “compromised clients’ assets and private property rights without regard to the law and due procedures”.

The letter, as per the Times’ report, also asks the bank to provide a “formal explanation” for its decision to freeze the accounts and urges it to publicly commit to “protecting the access to funds of individuals and their families subject to politically motivated charges issued by the Chinese and Hong Kong authorities”.

Hui, a former Hong Kong lawmaker, had said in December his local bank accounts appeared to have been frozen after he said he would exile himself in Britain to continue his pro-democratic activities.

British lawmaker Chris Bryant had also told the bank’s Chief Executive Noel Quinn last month that HSBC was “aiding and abetting one of the biggest crackdowns on democracy in the world”, during a hearing over its freezing of Hong Kong democrats’ bank accounts.