Thousands have signed an online petition denouncing reported comments by an HSBC Holdings board member in which she likened Hong Kong protesters' demands for democracy to the emancipation of slaves.

Laura Cha, who is also a member of Hong Kong's policymaking Executive Council, chairwoman of the city's Financial Services Development Council and a member of China's parliament, was quoted as making the comments at an event in Paris.

"American slaves were liberated in 1861 but did not get voting rights until 107 years later. So why can't Hong Kong wait for a while?" the Standard newspaper on Thursday quoted Cha as saying, referring to demands for free elections in the former British colony.