Catholic priests in Hong Kong have been warned over the content of their sermons after the implementation of the National Security Law. 

The Tablet reports that Cardinal John Tong has written to priests asking that they refrain from "instigating hatred and social disorder". 

Sermons should not "lose touch" with the "concrete situation of society", the cardinal wrote, but they should also not "convey the preacher's personal views (such as his own view on a social or political issue) but God's message". 

"In a critical time like today, our faithful are hoping to hear something comforting, constructive and encouraging from the preachers during the liturgy," he said. 

The stance differs from that of emeritus Bishop of Hong Kong, Cardinal Zen, who said he would continue to speak up despite the risk of imprisonment. 

"If such right and proper words are considered to be against their law, I will endure all the suing, trials and arrests. Numerous predecessors have endured similarly. We have seen how God has always helped them," he said.