Six pro-democracy activists told Reuters that Hong Kong police obtained some of their bank records without their consent and questioned them about certain transactions after they were arrested earlier this month on suspicion of subversion under the territory’s national security law.

The number of requests for customers’ financial records by Hong Kong police has more than doubled over the past six months or so, an executive at a major retail bank in Hong Kong with direct knowledge of the matter told Reuters. The executive said the number of people affected likely remains in double figures overall. The person said the increase was due to requests for information about pro-democracy activists.

The increasing use of bank records in questioning activists, which has not previously been reported, shows police in the Chinese-run city are using the full extent of their powers to investigate people suspected of breaking the stringent national security law which was introduced on June 30, according to the six activists.

Some of the banks involved include HSBC Holdings Plc and its Hang Seng Bank Ltd subsidiary, Citigroup Inc unit Citibank and Standard Chartered Plc. Representatives of those banks declined to comment on individual accounts.

Banks in Hong Kong have little choice but to comply with police requests, the senior bank executive told Reuters: “The aggrieved party can go to the court if they think their accounts were frozen or their transaction details were shared for wrong reasons, but there’s very little we can do here.”

A Hong Kong police representative declined to comment on why officers were seeking activists’ financial records, saying the department would not disclose details of its operations or investigations. The Hong Kong government did not respond to a request for comment on how or why police sought the bank information of arrested suspects.

Police in Hong Kong, as in most places in the world, have long been able to request customer information from banks as part of criminal investigations. Reuters could not determine whether the national security law has made it easier for police to get hold of individuals’ bank records.

The law does not mention access to bank information. It does give authorities the power to seize funds they believe are the proceeds of, or are intended to be used for, breaking the national security law. Authorities have not announced the seizure of any funds under that provision.

A spokeswoman for the Hong Kong Monetary Authority, which regulates the banking sector, said: “Financial institutions are expected to cooperate with (law enforcement agencies) on investigations and law enforcement actions.”

CROWDFUNDING CAMPAIGN FOR VOTE

Ninety-four people have been arrested under the national security law, which punishes anything authorities regard as secession, subversion, terrorism or collusion with foreign forces with up to life in prison.

China’s parliament imposed the law on Hong Kong in response to sometimes violent protests in 2019. The protests were prompted by fears that Beijing was stifling the city’s freedoms, guaranteed by the “one country, two systems” formula agreed when Hong Kong returned to Chinese rule in 1997. Authorities in Beijing and Hong Kong say the law is only aimed at a few “troublemakers” and not wider rights that underpin the city’s role as a gateway for capital flows in to and out of China.

The six activists who spoke to Reuters were among 53 arrested in a dawn sweep on Jan. 6. They were questioned about their roles in a July vote organized by pro-democracy parties to choose candidates for a legislative council election that was scheduled for September. The legislative council election was later postponed. The Hong Kong government has described the pro-democracy vote as part of an attempt to overthrow the government. None of the arrested activists have been charged and all have been released on bail.

One of the arrested activists, Owen Chow, told Reuters that police obtained his financial records from Citibank, Hang Seng Bank and PayMe, a phone payment app operated by HSBC, and asked him about the source of funds of up to HK$100,000 ($13,000) paid into the three accounts. He said police confiscated his debit and credit cards issued by Citibank and Hang Seng Bank.