Police have revoked a fake ID and hukou (residence permit) they say was used by a former deputy bank chief in Shenmu county, Shaanxi province, to buy some 20 properties reportedly valued at 1 billion yuan ($160 million).

The China Banking Regulatory Commission's office in Shaanxi is investigating. An official at the office was reached by phone on Sunday, but he declined to comment.

Gong Aiai, 49, a former deputy chief of the Shenmu Rural Commercial Bank, was accused in an online posting of having two identity cards and owning more than 20 properties in Beijing with an estimated value of 1 billion yuan.

Police say Gong registered a fake ID card by using her real photo, but under a different name, Gong Xianxia. The police station that handled her application issued a statement on Saturday saying police officers were negligent when registering her information.

The bank in Shenmu dismissed Gong after a meeting on Saturday.

In response to public concern about how she could afford the houses, Gong told Xinhua News Agency on Friday that the properties were purchased with profits made from her family's coal mine business.

She said some were purchases by her family members, and they have mortgages to pay for some houses, Xinhua reported.

She said she took a Taoist priest's suggestion and registered a fake ID card for superstitious reasons, not to intentionally get around property purchase regulations, Xinhua reported.

Gong had sent her resignation to the bank in June 2012 so that she could focus on the family business, the report said.

Gong's case is the second in which people were accused of acquiring property holdings by using double residence permits.

Earlier this month, former housing administration official Zhai Zhenfeng was arrested on suspicion of corruption after a whistleblower revealed that his family owned 31 houses in Zhengzhou, Henan province.

Zhai's daughter owned 11 houses that were bought in an affordable-housing project. Zhai, his wife, their son and daughter all had two residence permits, which police have nullified.

The effectiveness of online whistleblowers has been demonstrated by the quick downfall of numerous officials who were accused of corruption, using their public office for personal gains, or keeping mistresses.

Disciplinary authorities in major cities across China have opened accounts on social networks to ask the public to provide useful information.

Disciplinary watchdogs in Nanjing, Jiangsu province, opened an account on Sina Weibo, a micro-blogging website, in September. The latest big case they handled with online updates involved a traffic police officer who agreed not to give drivers a ticket if they bought coconut juice from a minivan he pointed them toward.

The case spread on the Internet on Jan 3. The next day, the micro blog released a post saying that the police officer had been suspended from duty.

In Huai'an, Jiangsu province, a similar online platform opened in Aug 2011. By the end of 2012, authorities in Huai'an investigated 52 cases by following online whistleblowers' information. Twenty people were removed from their posts, Xinhua Daily reported in the province on Friday.

Contact the writers at liyao@chinadaily.com.cn and luhongyan@chinadaily.com.cn