HONG KONG (AP) — Hong Kong Chief Executive John Lee condemned an unusual rise in the number of withdrawal requests to the city’s organ donation system, saying Tuesday that police would investigate suspicious cases.

According to the government, the city’s centralized organ donation registration system received nearly 5,800 withdrawal applications in the five months since December, when the government raised the possibility of establishing an organ transplant mutual assistance program with mainland China. More than half of the withdrawal applications were found to be invalid, either as duplicate applications or coming from people who had never opted in.

At a regular press briefing, Lee pointed to those who withdrew their applications without ever registering, calling the moves suspicious.

“I severely condemn those who attempt to cause damages to this noble system which saves lives through organ donations,” he said. “This is a shameful act.”

The government also issued a strong-worded statement Monday, saying it could not rule out that a small number of people made withdrawal attempts in a bid to undermine the reputation of the system, and to increase administrative burden. Without naming any platforms or any individuals, it said it noticed a small number of people had distorted the virtue of organ donation by promoting the idea that donors should scrutinize the identity of the recipients online. Some also urged others to withdraw from the system, it added.

On Hong Kong’s Reddit-like forum LIHKG — where pro-democracy supporters discussed strategies for the 2019 anti-government movement — some users were skeptical about the proposed system. Others posted a link for making withdrawals from the register.

The government floated the proposal after a baby girl underwent the city’s first transplant using an organ donated from mainland China in December. It said the organ assistance program under consideration could be activated immediately after medical personnel could not match a donated organ with a suitable patient locally.

The political row over the proposed mutual assistance program reflected some Hong Kongers’ distrust of China’s health system, as well as their grievances toward Beijing, which has cracked down on the city’s pro-democracy movement with a sweeping national security law.